New Publications of the
U.S. Geological Survey

For Immediate Release ...

The U.S. Geological Survey makes every effort to ensure that all of its publications are made available equally and fairly to everyone. To ensure fairness while expediting the release of important information, this list supplements New Publications of the U.S. Geological Survey by announcing the immediate availability of some publications. The authors of the publications below have requested to be included in the list. All publications will be included in later issues of the monthly catalog.

October 27, 2004

OFR 2004-1318. TENNESSEE.

Base-Flow Data in the Arnold Air Force Base Area, Tennessee, June and October 2002. By John A. Robinson and Connor J. Haugh, 26 pages.

Available from the U.S. Geological Survey Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Open-File Report 2004-1318, 26 p., 6 figs.

Available on line.

Arnold Air Force Base (AAFB) occupies about 40,000 acres in Coffee and Franklin Counties, Tennessee. The primary mission of AAFB is to support the development of aerospace systems. This mission is accomplished through test facilities at Arnold Engineering Development Center (AEDC), which occupies about 4,000 acres in the center of AAFB. Base-flow data including discharge, temperature, and specific conductance were collected for basins in and near AAFB during high base-flow and low base-flow conditions. Data representing high base-flow conditions from 109 sites were collected on June 3 through 5, 2002, when discharge measurements at sites with flow ranged from 0.005 to 46.4 ft³/s. Data representing low base-flow conditions from 109 sites were collected on October 22 and 23, 2002, when discharge measurements at sites with flow ranged from 0.02 to 44.6 ft³/s. Discharge from the basin was greater during high base-flow conditions than during low base-flow conditions. In general, major tributaries on the north side and southeastern side of the study area (Duck River and Bradley Creek, respectively) had the highest flows during the study.

Discharge data were used to categorize stream reaches and sub-basins. Stream reaches were categorized as gaining, losing, wet, dry, or unobserved for each base-flow measurement period. Gaining stream reaches were more common during the high base-flow period than during the low base-flow period. Dry stream reaches were more common during the low base-flow period than during the high base-flow period. Losing reaches were more predominant in Bradley Creek and Crumpton Creek.

Values of flow per square mile for the study area of 0.55 and 0.37 (ft³/s)/mi² were calculated using discharge data collected on June 3 through 5, 2002, and October 22 and 23, 2002, respectively. Sub-basin areas with surplus or deficient flow were defined within the basin. Drainage areas for each stream measurement site were delineated and measured from topographic maps. Change in flow per square mile for each sub-basin was calculated using data from each base-flow measurement period. The calculated values were used to define the areas of surplus or deficient flow for high and low base-flow conditions. Many areas of deficient flow were present throughout the study area under high and low base-flow conditions. Most areas of deficient flow were in the headwater basins. Fewer areas of surplus flow were present under low base-flow conditions than during the high base-flow conditions. The flow per square mile for each major tributary basin in the study area also was calculated. The values of flow per square mile for the Dry Creek, Spring Creek, and Wiley Creek basins were greatest under both high and low base-flow conditions.

October 21, 2004

SIR 2004-5158. NEW MEXICO.

Ground-water hydrology and water quality of the Southern High Plains aquifer, Melrose Air Force Range, Cannon Air Force Base, Curry and Roosevelt Counties, New Mexico, 2002-03. By Jeff B. Langman, Fredrick E. Gebhardt, and Sarah E. Falk, 42 pages.

Available from U.S. Geological Survey Information Services, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS SIR 2004-5158, 42 p., 14 figs. Also available from the New Mexico District Office, U.S. Geological Survey, 5338 Montgomery Blvd. NE, Suite 400, Albuquerque, NM 87109.

Available on line.

In cooperation with the U.S. Air Force, the U.S. Geological Survey characterized the ground-water hydrology and water quality at Melrose Air Force Range in east-central New Mexico. The purpose of the study was to provide baseline data to Cannon Air Force Base resource managers to make informed decisions concerning actions that may affect the ground-water system. Five periods of water-level measurements and four periods of water-quality sample collection were completed at Melrose Air Force Range during 2002 and 2003. The water-level measurements and water-quality samples were collected from a 29-well monitoring network that included wells in the Impact Area and leased lands of Melrose Air Force Range managed by Cannon Air Force Base personnel. The purpose of this report is to provide a broad overview of ground-water flow and ground-water quality in the Southern High Plains aquifer in the Ogallala Formation at Melrose Air Force Range.

Results of the ground-water characterization of the Southern High Plains aquifer indicated a local flow system in the unconfined aquifer flowing northeastward from a topographic high, the Mesa (located in the southwestern part of the Range), toward a regional flow system in the unconfined aquifer that moves southeastward through the Portales Valley. Ground water was less than 55 years old across the Range; ground water was younger (less than 25 years) near the Mesa and ephemeral channels and older (25 years to 55 years)in the Portales Valley. Results of water-quality analysis indicated three areas of different water types: near the Mesa and ephemeral channels, in the Impact Area of the Range, and in the Portales Valley. Within the Southern High Plains aquifer, a sodium/chloride-dominated ground water was found in the center of the Impact Area of the Range with water-quality characteristics similar to ground water from the underlying Chinle Formation. This sodium/chloride-dominated ground water of the unconfined aquifer in the Impact Area indicates a likely connection with the deeper water-producing zone. No pesticides, explosives, volatile organic compounds, semivolatile organic compounds, organic halogens, or perchlorate were found in water samples from the Southern High Plains aquifer at the Range.

October 21, 2004

SIR 2004-5138. MINNESOTA.

Presence and distribution of organic wastewater compounds in wastewater, surface, ground, and drinking waters, Minnesota, 2000-02. By K.E. Lee, L.B.Barber, E.T. Furlong, J.D. Cahill, D.W. Kolpin, M.T. Meyer, and S.D. Zaugg, 47 pages.

Availble from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigation Report 2004-5138, 47 p.

Selected organic wastewater compounds (OWCs) such as household, industrial, and agricultural-use compounds, pharmaceuticals, antibiotics, and sterols and hormones were measured at 65 sites in Minnesota as part of a cooperative study among the Minnesota Department of Health, Minnesota Pollution Control Agency, and the U.S. Geological Survey. Samples were collected in Minnesota during October 2000 through November 2002 and analyzed for the presence and distribution of 91 OWCs at sites including wastewater treatment plant influent and effluent; landfill and feedlot lagoon leachate; surface water; ground water (underlying sewered and unsewered mixed urban land use, a waste dump, and feedlots); and the intake and finished drinking water from drinking water facilities.

There were 74 OWCs detected that represent a wide variety of use. Samples generally comprised a mixture of compounds (average of 6 OWCs) and 90 percent of the samples had at least one OWC detected. Concentrations for detected OWCs generally were less than 3 micrograms per liter. The ten most frequently detected OWCs were metolachlor (agricultural-use herbicide); cholesterol (sterol primarily associated with animal waste); caffeine (stimulant), N,N-diethyl-meta-toluamide (DEET) (topical insect repellant); bromoform (disinfection by product); tri(2-chloroethyl)phosphate (flame-retardant and plastic component); beta-sitosterol (plant sterol that is a known endocrine disruptor); acetyl-hexamethyl-tetrahydro-naphthalene (AHTN) (synthetic musk widely used in personal care products, and a known endocrine disruptor); bisphenol-A (plastic component and a known endocrine disruptor); and cotinine (metabolite of nicotine).

Wastewater treatment plant influent and effluent, landfill leachate, and ground water underlying a waste dump had the greatest number of OWCs detected. OWC detections in ground-water were low except underlying the one waste dump studied and feedlots. There generally were more OWCs detected in surface water than ground water, and there were twice as many OWCs detected in the surface water sites downstream from wastewater treatment plant (WWTP effluent than at sites not directly downstream from effluent. Comparisons among site classifications apply only to sites sampled during the study.

Results of this study indicate ubiquitous distribution of measured OWCs in the environment that originate from numerous sources and pathways. During this reconnaissance of OWCs in Minnesota it was not possible to determine the specific sources of OWCs to surface, ground, or drinking waters. The data indicate WWTP effluent is a major pathway of OWCs to surface waters and that landfill leachate at selected facilities is a potential source of OWCs to WWTPs. Aquatic organism or human exposure to some OWCs is likely based on OWC distribution. Few aquatic or human health standards or criteria exist for the OWCs analyzed, and the risks to humans or aquatic wildlife are not known. Some OWCs detected in this study are endocrine disrupters and have been found to disrupt or influence endocrine function in fish. Thirteen endocrine disrupters, 3-tert-butyl-4-hydoxyanisole (BHA), 4-cumylphenol, 4-normal-octylphenol, 4-tert-octylphenol, acetyl-hexamethyl-tetrahydro-naphthalene (AHTN), benzo[a]pyrene, beta-sitosterol, bisphenol-A, diazinon, nonylphenol diethoxylate (NP2EO), octyphenol diethoxylate (OP2EO), octylphenol monoethoxylate (OP1EO), and total para-nonylphenol (NP) were detected. Results of reconnaissance studies may help regulators who set water-quality standards begin to prioritize which OWCs to focus upon for given categories of water use.

October 21, 2004

SIR 204-5159. MINNESOTA.

Simulation of ground-water flow in glaciofluvial aquifers in the Grand Rapids area, Minnesota. By P.M. Jones, 23 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225,USGS Scientific Investigation Report 2004-5159, 23 p. 7 figs.

A calibrated steady-state, finite-difference, ground-water-flow model was constructed to simulate ground-water flow in three glaciofluvial aquifers, defined in this report as the upper, middle, and lower aquifers, in an area of about 114 mi² surrounding the city of Grand Rapids in north-central Minnesota. The calibrated model will be used by Minnesota Department of Health and communities in the Grand Rapids area in the development of wellhead protection plans for their water supplies. The model was calibrated through comparison of simulated ground-water levels to measured static water levels in 351 wells, and comparison of simulated base-flow rates to estimated base-flow rates for reaches of the Mississippi and Prairie Rivers. Model statistics indicate that the model tends to overestimate ground-water levels. The root mean square errors ranged from +12.83 ft in wells completed in the upper aquifer to +19.10 ft in wells completed in the middle aquifer. Mean absolute differences between simulated and measured water levels ranged from +4.43 ft for wells completed in the upper aquifer to +9.25 ft for wells completed in the middle aquifer. Mean algebraic differences ranged from +9.35 ft for wells completed in the upper aquifer to +14.44 ft for wells completed in the middle aquifer, with the positive differences indicating that the simulated water levels were higher than the measured water levels. Percentage errors between simulated and estimated base-flow rates for the three monitored reaches all were less than 10 percent, indicating good agreement. Simulated ground-water levels were most sensitive to changes in general-head boundary conductance, indicating that this characteristic is the predominant model input variable controlling steady-state water-level conditions. Simulated ground-water flow to stream reaches was most sensitive to changes in horizontal hydraulic conductivity, indicating that this characteristic is the predominant model input variable controlling steady-state flow conditions.

October 20, 2004

OFR 2004-1347. NEW MEXICO.

Rainfall, runoff, and water-quality data for the urban storm-water program in the Albuquerque, New Mexico, metropolitan area, water year 2002. By Todd Kelly, Orlando Romero, and Eric Turner, 119 pages.

Available from U.S. Geological Survey Information Services, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Open-File Report 2004-1347, 119 p., 9 figs.

Urbanization has dramatically increased precipitation runoff to the system of drainage channels and natural stream channels in the Albuquerque, New Mexico, metropolitan area. Rainfall and runoff data are important for planning and designing future storm-water conveyance channels in newly developing areas. Storm-water quality also is monitored in accordance with the National Pollutant Discharge Elimination System mandated by the U.S. Environmental Protection Agency. The Albuquerque Metropolitan Arroyo Flood Control Authority, the City of Albuquerque, and the U.S. Geological Survey began a cooperative program to collect hydrologic data to help assess the quality and quantity of surface-water resources in the Albuquerque area. This report presents water-quality, streamflow, and rainfall data collected from October 1, 2001, to September 30, 2002 (water year 2002). Also provided is a station analysis for each of the 20 streamflow-gaging sites and 41 rainfall-gaging sites, which includes a description of monitoring equipment, problems associated with data collection during the year, and other information used to compute streamflow discharges or rainfall records. A hydrographic comparison shows the effects that the largest drainage channel in the metropolitan area, the North Floodway Channel, has on total flow in the Rio Grande.

October 19, 2004

OFR 2004-1277. ARKANSAS.

Stream habitat and water-quality information for sites in the Buffalo River Basin and nearby basins of Arkansas, 2001-2002. By James C. Petersen, 11 pages.

Available from the U.S. Geological Survey, Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Open-File Report 2004-1277, 11 p., 1 fig., and 3 tables

Available on line.

The Buffalo River lies in north-central Arkansas and is a tributary of the White River. Stream-habitat and water-quality information are presented for 52 sites in the Buffalo River Basin and adjacent areas of the White River Basin. The information was collected during the summers of 2001 and 2002 to supplement fish community sampling during the same time period.

October 19, 2004

SIR 2004-5119. ARKANSAS.

Fish communities of the Buffalo River Basin and nearby basins of Arkansas and their relation to selected environmental factors, 2001-2002. By James C. Petersen, 93 pages.

Available from the U.S. Geological Survey, Information Services, Box 25286, Denver Federal Center, Denver, CO 80225 USGS Scientific Investigations Report 2004-5119, 93 p., 11 fig., and 16 tables.

The Buffalo River lies in north-central Arkansas and is a tributary of the White River. Most of the length of the Buffalo River lies within the boundaries of Buffalo National River, a unit of the National Park Service; the upper 24 river kilometers lie within the boundary of the Ozark National Forest. Much of the upper and extreme lower parts of the basin on the south side of the Buffalo River is within the Ozark National Forest.

During the summers of 2001 and 2002, fish communities were sampled at 52 sites in the study area that included the Buffalo River Basin and selected smaller nearby basins within the White River Basin in north-central Arkansas. Water quality (including nutrient and bacteria concentrations) and several other environmental factors (such as stream size, land use, substrate size, and riparian shading) also were measured.

A total of 56 species of fish were collected from sites within the Buffalo River Basin in 2001 and 2002. All 56 species also were collected from within the boundaries of Buffalo National River. Twenty-two species were collected from headwater sites on tributaries of the Buffalo River; 27 species were collected from sites within or immediately adjacent to the Ozark National Forest. The list of species collected from Buffalo National River is similar to the list of species reported by previous investigators. Species richness at sites on the mainstem of the Buffalo River generally increased in a downstream direction. The number of species collected (both years combined) increased from 17 at the most upstream site to 38 near the mouth of the Buffalo River. In 2001 and 2002, a total of 53 species of fish were collected from sites outside the Buffalo River Basin.

Several fish community metrics varied among sites in different site categories (mainstem, large tributary, small tributary, headwater, and developed out-of-basin sites). Median relative abundances of stonerollers ranged from about 25 to 55 percent and were highest at headwater and developed out-of-basin sites and lowest at mainstem sites. The relative abundances at the headwater and developed out-of-basin sites were significantly different from the relative abundances at the mainstem sites. Percentages of individuals of algivorous/herbivorous, invertivorous, and piscivorous species at headwater sites were significantly lower than values at mainstem and developed out-of-basin sites. Percentages of individuals of invertivorous species at mainstem sites were significantly higher than values at small tributary, headwater, and developed out-of-basin sites. Percentages of top carnivores at mainstem sites were significantly higher than values at tributary and headwater sites. The numbers of darter, sculpin, plus madtom species at mainstem, large tributary, and developed out-of-basin sites were significantly higher than values at other sites, and the values at small tributary sites and headwater sites were each significantly different from values at the other four types of sites. The number of lithophilic spawning species at large tributary sites was not significantly different from values at mainstem and developed out-of-basin sites, but values for small tributary and headwater sites each were significantly different from values for all other categories. Index of biotic integrity scores varied among the site categories. Scores for mainstem sites were significantly larger than all but large tributary site scores. Scores for headwater sites were significantly smaller than mainstem and large tributary site scores.

Several analyses of the data described in this report suggest that drainage area is the most important single factor influencing fish communities of the Buffalo River Basin and nearby basins. Species richness increases with increasing drainage area and some species are restricted to smaller streams while other species are more common in larger streams. Some community metrics also are related to land use and related factors (proportion of cleared land and nutrient concentrations, for example), suggesting that substantial shifts in basin land use or point-source effluents will have effects on downstream fish communities.

October 19, 2004

WRI 03-4331. INDIANA.

Biological Assessment of Streams in the Indianapolis Metropolotian Area, Indiana, 1999-2001. By D.C. Voelker, 48 pages.

Printed copies are available through the USGS Indiana District, 5957 Lakeside Boulevard, Indianapolis, IN 46278 (phone 317-290-3333) or through USGS Information Services, Box 25286, Denver Federal Center, Denver, CO 80225

During 1999-2001, benthic invertebrates and fish were sampled to describe biological communities in the White River and selected tributaries in the Indianapolis Metropolitan Area in Indiana. Twelve sites (six on the White River and six on tributaries) were sampled biannually for benthic invertebrates and annually for fish. The information complements water-chemistry data collected by the Indianapolis Department of Public Works in the study area. Evaluation of the habitat for sites in the study area was done, using a Qualitative Habitat Evaluation Index (QHEI) developed by the Ohio Environmental Protection Agency. The QHEI scores basin and habitat characteristics for each site, with a maximum possible score of 100. Higher scores indicate better habitat conditions for biotic communities. The QHEI scores for sites on the White River ranged from 55 at the Harding site to 71 at the Waverly site; scores on the tributaries ranged from 45 on Pogues Run to 82 on Williams Creek.

A total of 151 taxa were identified from the benthic- invertebrate samples. The Ephemeroptera, Plecoptera, and Trichoptera (EPT) Index scores for sites on the White River ranged from 0 at the Harding site to 15 at the Nora site. The Nora site, which is upstream from Indianapolis, generally scored the highest of all White River sites. Sites in the immediate vicinity of Indianapolis scored the lowest and indicate a negative effect on benthic-invertebrate communities in that reach. EPT Index scores increased in the farthest downstream reaches, which indicate that water-quality conditions had improved in comparison to sites in Indianapolis. For the tributary sites, EPT Index values ranged from 0 at Pogues Run to 16 at Buck Creek. Tributary sites on Fall Creek, Pleasant Run, and Pogues Run consistently scored 7 or lower; sites on Buck Creek, Eagle Creek, and Williams Creek scored 7 or higher.

Hilsenhoff Biotic Index (HBI) scores ranged from 4.9 (good) to 9.6 (very poor) for the White River sites and from 5.2 (good) to 8.0 (poor) for the tributary sites. The lowest scores among the White River sites were at the Nora site, indicating the best water-quality conditions were where the White River enters Marion County. The highest HBI scores were at the Morris and Harding sites, indicating the least-favorable water-quality conditions of all the White River sites. Of the tributary sites, HBI scores for Buck, Eagle, and Williams Creeks indicate fair water-quality conditions; HBI scores for Pleasant Run and Pogues Run were the highest, indicating relatively poor water-quality conditions.

On the White River, the highest Invertebrate Community Index (ICI) scores, which indicate the best benthic-invertebrate conditions, were at the Nora site. Conditions were fair to poor in the downtown Indianapolis area; ICI scores indicate slight improvement in the downstream reaches of the study area. Of the tributary sites, Buck Creek was the only site with ICI scores indicating exceptional water quality. Williams Creek ICI scores indicate good water quality; the remaining tributary- site scores reflect fair conditions.

A total of 74 species and 3 hybrids of fish were identified during the study period. The Cyprinidae (carps and minnows) was the largest group of fish identified and consisted of more than half of all fish collected. The most numerous species was the central stoneroller (Campostoma anomalum), which accounted for almost 25 percent of the fish identified. Two nonnative species, the koi carp (Cyprinus carpio) and the western mosquitofish (Gambusia affinis), and one species classified as an Indiana species of special concern, the northern studfish (Fundulus catenatus), also were collected during the study.

Indiana Index of Biotic Integrity (IBI) and Ohio Index of Biotic Integrity scores were calculated to show the condition of the fish communities at each site. Results of the Indiana IBI calculations showed no apparent differences in scores among the White River sites. Among the tributary sites, however, scores from the Pleasant Run and Pogues Run sites indicate conditions at those sites were less favorable than at the other tributary sites.

Results of the study were affected by an accidental discharge at Anderson, Indiana, where toxic chemicals were released into the White River in December 1999. The discharge resulted in the death of an estimated 117 tons of fish along more than 50 miles of the White River from Anderson to south of Indianapolis. Biologists began restocking various reaches of the river with channel catfish (Ictalurus punctatus) fingerlings and adult channel catfish (Ictalurus punctatus), flathead catfish (Pylodictis olivaris), largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu), rock bass (Am-bloplites rupestris), bluegill (Lepomis macrochirus), redear sunfish (Lepomis microlophus), and white crappie (Pomoxis annularis) from April 2000 through November 2001. In addition to the changes in the fish population, the direct and indirect effect on the benthic-invertebrate community was not clear.

Since 1981, the U.S. Geological Survey has collected benthic invertebrates intermittently at or near three sites (Nora, Stout, and Waverly) on the White River. Historically, benthic-invertebrate data at the Nora site indicate generally good conditions as the White River enters the Indianapolis Metropolitan Area. At the Stout site, however, benthic-invertebrate data indicate that conditions were consistently more degraded than at the other two sites. At the Waverly site, data indicate some recovery in water quality, although conditions were not as good as at the Nora site.

Fish data collected during this study also were compared to a compilation of fish species historically found in the White River Basin. Two species collected in this study-the Ohio lamprey (Ichthyomyzon bdellium) and the banded darter (Etheostoma zonale)-were not reported in that compilation.

October 19, 2004

other 2004-3097. COLORADO, KANSAS, NEBRASKA, NEW MEXICO, OKLAHOMA, SOUTH DAKOTA, TEXAS, and WYOMING.

Water-level changes in the High Plains aquifer, predevelopment to 2003 and 2002 to 2003. By Virginia L. McGuire, 6 pages.

Available from the U.S. Geological Survey Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Fact Sheet 2004-3097, 6 p., 4 figs.

Available on line.

This fact sheet describes changes that have taken place in the High Plains aquifer from the time that substantial ground-water pumping began, which was generally from the 1930's to the 1950's, and is termed "predevelopment," to the year 2003. According to this report, water in storage in the High Plains (or Ogallala) aquifer declined about 235 million acre-feet from predevelopment to 2003 and 19 million acre-feet from 2002 to 2003.

Underlying parts of eight states, including Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, and Texas, the High Plains aquifer spans 173,000 square miles, provides irrigation for one of the major agricultural regions in the nation, and supplies drinking water for 82 percent of the people who live within the aquifer boundaries. Water levels in the High Plains aquifer started to decline soon after the beginning of extensive ground-water irrigation development. USGS scientists mapped water-level changes using data collected by the USGS, and other Federal, State, and local agencies between the years 1920 and 2003 from more than 20,000 wells screened in the High Plains aquifer. A network of about 9,200 wells was used to monitor water levels in the aquifer in 2003. The predevelopment water level generally was estimated by using the earliest water-level measurement available. USGS scientists calculated change in water in storage using the maps of water-level changes for each comparison period and the average specific yield of the aquifer.

October 13, 2004

other SIR2004-5205. NEVADA, CALIFORNIA.

Death Valley Regional Ground-Water Flow System, Nevada and California.Hydrogeologic Framework and Transient Ground-Water Flow Model. By Wayne R. Belcher, Claudia C. Faunt, Donald S. Sweetkind, Carma A. San Juan, Joan B. Blainey, Randell J. Laczniak, Mary C. Hill, Frank A. D'Agnese, Grady M. O.Brien, Christopher J. Potter, M.S. Bedinger, J.R. Harrill, and Heather M. Putnam, 408 pages.

Available on line.

A numerical three-dimensional (3D) transient groundwater flow model of the Death Valley region was developed by the U.S. Geological Survey for the U.S. Department of Energy programs at the Nevada Test Site and at Yucca Mountain, Nevada. Decades of study of aspects of the ground-water flow system and previous less extensive ground-water flow models were incorporated and reevaluated together with new data to provide greater detail for the complex, digital model.

A 3D digital hydrogeologic framework model (HFM) was developed from digital elevation models, geologic maps, borehole information, geologic and hydrogeologic cross sections, and other 3D models to represent the geometry of the hydrogeologic units (HGUs). Structural features, such as faults and fractures, that affect ground-water flow also were added. The HFM represents Precambrian and Paleozoic crystalline and sedimentary rocks, Mesozoic sedimentary rocks, Mesozoic to Cenozoic intrusive rocks, Cenozoic volcanic tuffs and lavas, and late Cenozoic sedimentary deposits of the Death Valley regional ground-water flow system (DVRFS) region in 27 HGUs.

Information from a series of investigations was compiled to conceptualize and quantify hydrologic components of the ground-water flow system within the DVRFS model domain and to provide hydraulic-property and head-observation data used in the calibration of the transient-flow model. These studies reevaluated natural ground-water discharge occurring through evapotranspiration (ET) and spring flow; the history of ground-water pumping from 1913 through 1998; groundwater recharge simulated as net infiltration; model boundary inflows and outflows based on regional hydraulic gradients and water budgets of surrounding areas; hydraulic conductivity and its relation to depth; and water levels appropriate for regional simulation of prepumped and pumped conditions within the DVRFS model domain. Simulation results appropriate for the regional extent and scale of the model were provided by acquiring additional data, by reevaluating existing data using current technology and concepts, and by refining earlier interpretations to reflect the current understanding of the regional ground-water flow system.

Ground-water flow in the Death Valley region is composed of several interconnected, complex ground-water flow systems. Ground-water flow occurs in three subregions in relatively shallow and localized flow paths that are superimposed on deeper, regional flow paths. Regional ground-water flow is predominantly through a thick Paleozoic carbonate rock sequence affected by complex geologic structures from regional faulting and fracturing that can enhance or impede flow. Spring flow and ET are the dominant natural groundwater discharge processes. Ground water also is withdrawn for agricultural, commercial, and domestic uses.

Ground-water flow in the DVRFS was simulated using MODFLOW-2000, a 3D finite-difference modular groundwater flow modeling code that incorporates a nonlinear least-squares regression technique to estimate aquifer parameters. The DVRFS model has 16 layers of defined thickness, a finite-difference grid consisting of 194 rows and 160 columns, and uniform cells 1,500 meters (m) on each side.

Prepumping conditions (before 1913) were used as the initial conditions for the transient-state calibration. The model uses annual stress periods with discrete recharge and discharge components. Recharge occurs mostly from infiltration of precipitation and runoff on high mountain ranges and from a small amount of underflow from adjacent basins. Discharge occurs primarily through ET and spring discharge (both simulated as drains) and water withdrawal by pumping and, to a lesser amount, by underflow to adjacent basins, also simulated by drains. All parameter values estimated by the regression are reasonable and within the range of expected values. The simulated hydraulic heads of the final calibrated transient model generally fit observed heads reasonably well (residuals with absolute values less than 10 m) with two exceptions: in most areas of nearly flat hydraulic gradient the fit is considered moderate (residuals with absolute values of 10 to 20 m), and in areas of steep hydraulic gradient, such as Indian Springs, western Yucca Flat, and the southern part of the Bullfrog Hills, the fit is poor (residuals with absolute values greater than 20 m). Ground-water discharge residuals are fairly random, with as many areas where simulated flows are less than observed flows as areas where simulated flows are greater. The highest unweighted ground-water discharge residuals occur at Death 2 Death Valley Regional Ground-Water Flow System Transient Flow Model Valley and Ash Meadows. High weighted discharge residuals were computed in the Pahrump Valley, possibly indicating a poor definition of hydraulic properties or discharge estimates in that area.

The model represents the large and complex groundwater flow system of the Death Valley region at a greater degree of refinement and accuracy than has been possible previously. The representation of detail provided by the 3D digital hydrogeologic framework model and the numerical ground-water flow model enabled greater spatial accuracy in every model parameter. The lithostratigraphy and structural effects of the hydrogeologic framework; recharge estimates from simulated net infiltration; discharge estimates from ET, spring flow, and pumping; and boundary inflow and outflow estimates all were reevaluated, some additional data were collected, and accuracy was improved. Uncertainty in the results of the flow model simulations can be reduced by improving on the quality, interpretation, and representation of the waterlevel observations used to calibrate the model and improving on the representation of the HGU geometries, the spatial variability of HGU material properties, the flow model physical framework, and the hydrologic conditions.

October 7, 2004

Available from USGS Information Services, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Fact Sheet 2004-3081.

When the City of Albuquerque begins using surface water instead of ground water as its primary source of municipal supply, substantial changes will occur in the river-aquifer system of the Middle Rio Grande Basin. Water levels in the aquifer system will change, as will the quantity of water stored in the aquifer system and the quantity of water that leaks into the aquifer system from the river system. This Fact Sheet describes the results of a model simulation to investigate the effects of projected ground-water withdrawals by the City of Albuquerque for 2004-40 on the river-aquifer system, assuming future water use per person is reduced.

October 4, 2004

SIR 2004-5061. OREGON.

Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988-2002. By Dwight Q. Tanner Karl K. Lee, 36 pages.

Available from U.S. Geological Survey, 10615 SE Cherry Blossom Dr., Portland, OR 97216, USGS Scientific Investigations Report 2004-5061, 36 p. E-mail info-or@usgs.gov

Also available from the U.S. Geological Survey Information Sevices, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5061, 36 p.

Available on line.

Organochlorine pesticides were detected in unfiltered samples from Johnson Creek that were collected during a storm in March, 2002. Total DDT (the sum of DDT and its metabolites), as well as dieldrin, potentially exceeded Oregon chronic, freshwater criteria at all four Johnson Creek stream-sampling sites. The total DDT criterion was also potentially exceeded at a storm drain at SE 45^th Avenue and Umatilla Street.

The concentration of total DDT in water samples has decreased by an order of magnitude since previous sampling was done on Johnson Creek in 1989-1990. This decrease was probably due to the movement of these compounds out of the basin and to degradation processes. Concentrations and loads of the organochlorine pesticides were largest at the most upstream sampling site, Johnson Creek at Palmblad Road, which has historically been primarily affected by agricultural land cover. Concentrations and loads were smaller at downstream locations, and there were only a few detections from storm drains.

For the purposes of assessing trends in total DDT concentration in Johnson Creek, data for total suspended solids (TSS) were examined, because TSS is often correlated with DDT concentrations, and TSS data are collected routinely by regulatory agencies. As an intermediate step, linear regression was used to relate TSS (measured in the recent study) and turbidity (measured both in the earlier and in the recent studies). For 77 samples, TSS (in mg/L [milligrams per liter]) = 0.88 x Turbidity (in nephleometric turbidity units). The r2 value was 0.82.

The TSS concentration (measured, or estimated by the regression) was compared to the concentration of total DDT using linear regression. The TSS concentration associated with meeting the Oregon water-quality criterion for total DDT was 15 to 18 mg/L in the lower and middle part of the basin and 8 mg/L in the upper reaches of the basin. This TSS/DDT relationship is based on only one storm and may not be valid for other conditions of streamflow and runoff. Dieldrin concentration was not well correlated with TSS.

Organochlorine compounds also were detected in significant concentrations in Kelley Creek, an important tributary to Johnson Creek, but quality-control considerations made it difficult to interpret some of the data. It does appear, however, that some of the metabolites of DDT were positively associated with TSS. The high concentrations of the DDT metabolites and dieldrin were correlated with agricultural areas.

September 30, 2004

Water-quality synoptic sampling, July 1999: North Fork Shenandoah River, Virginia. By Jennifer L. Krstolic and Donald C. Hayes, 82 p.

Available online only.

A study was conducted of water-quality conditions that may affect aquatic life during periods of low streamflow on the North Fork Shenandoah River, Va. Monthly mean streamflows in July 1999 at three streamflow-gaging stations were the lowest measured during the historical record on the river. Daily extremes of dissolved-oxygen concentrations were measured, along with pH, specific conductance,  and water-temperature values, at 52 sites along 80 mi of the North Fork Shenandoah River from Cootes Store, Va., to its confluence with Passage Creek, near Strasburg, Va.

Dissolved-oxygen concentrations ranged from 2.1 to 16.4 milligrams per liter (mg/L). Dissolved-oxygen concentrations were equal to or less than the State water-quality minimum of 4.0 mg/L at 18 of 52 monitoring sites; all 18 sites were in the upper and middle portions of the river, where more than half of the first 34 sites had minimum dissolved-oxygen concentrations equal to or less than 4.0 mg/L. There were large variations from minimum to maximum dissolved-oxygen concentrations, with concentrations fluctuating as much as 10 mg/L per day; and typically 5 mg/L per day during the study period.

pH ranged from 7.6 to 9.6, with pH values frequently greater than 9.0 in the downstream portion of the river. Specific-conductance values ranged from 178 to 856 microsiemens per centimeter (·S/cm), with values greater than 600 ·S/cm only measured at a group of five sites in the upstream portion of the river. Air temperatures ranged from 21.0 to 37.0 degrees Celsius (ºC), and water temperatures ranged from 17.00 to 30.14ºC. Along the length of the North Fork Shenandoah River, longitudinal variation in water-quality parameters was small. Groups of sites that differed from the general pattern define reaches where increased monitoring may help determine the factors that affect water quality at those sites.

September 29, 2004

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5149, 35 p., 12 figs.

Available on line.

Ground-water samples were collected from 90 active public supply wells in the Fresno and Modesto metropolitan areas as part of the California Aquifer Susceptibility (CAS) program. The CAS program was formed to examine the susceptibility to contamination of aquifers that are tapped by public supply wells to serve the citizens of California. The objectives of the program are twofold: (1) to evaluate the quality of ground water used for public supply using volatile organic compound (VOC) concentrations in ground-water samples and (2) to determine if the occurrence and distribution of low level VOCs in ground water and characteristics, such as land use, can be used to predict aquifer susceptibility to contamination from anthropogenic activities occurring at, or near, land surface. An evaluation was made of the relation between VOC occurrence and the explanatory variables: depth to the top of the uppermost well perforation, land use, relative ground-water age, high nitrate concentrations, density of leaking underground fuel tanks (LUFT), and source of recharge water. VOCs were detected in 92 percent of the wells sampled in Modesto and in 72 percent of the wells sampled in Fresno. Trihalomethanes (THM) and solvents were frequently detected in both study areas. Conversely, the gasoline components.benzene, toluene ethylbenzene, and xylenes (BTEX). were rarely, if at all, detected, even though LUFTs were scattered throughout both study areas. The rare occurrence of BTEX compounds may be the result of their low solubility and labile nature in the subsurface environment.

Samples were analyzed for 85 VOCs; 25 were detected in at least one sample. The concentrations of nearly all VOCs detected were at least an order of magnitude below action levels set by drinking water standards. Concentrations of four VOCs exceeded federal and state maximum contaminant levels (MCL): the solvent trichloroethylene (TCE) and the fumigant 1, 2-dibromo-3-chloropropane (DBCP) in Fresno, and the solvents TCE and tetrachloroethylene (PCE) in Modesto. Chloroform, which is a by product of water disinfection and a constituent used in industrial processes since the 1920s, was the most frequently detected compound, whereas the gasoline oxygenate methyl tert-butyl ether (MTBE), which has been in widespread production and use only since the 1990s, was detected in only 2 percent of the samples.

Downward migration of contaminants appears to be a viable pathway of contamination in the unconfined and semi-confined aquifers underlying the Fresno and Modesto study areas. Within the individual study areas, VOCs were detected more frequently and in greater numbers in shallower wells than in deeper wells. Additionally, VOCs were detected more frequently and in greater numbers in Modesto than in Fresno. Wells sampled in Modesto were significantly shallower than the wells sampled in Fresno; the other explanatory variables examined in this report were not significantly different between the two study areas.

VOCs occurred more frequently in younger ground water (water recharged after 1952) than in older ground water (water recharged prior to 1952). Additionally, wells withdrawing younger ground water had a higher number of VOCs detected per well than did wells withdrawing older ground water. Younger ground water was at or near the land surface during a period when VOCs came into widespread production and use. Therefore, wells from which younger ground water is withdrawn may be more susceptible to contamination.

Of the explanatory variables examined in this study, land use was the best predictor of aquifer susceptibility in the Fresno and Modesto study areas. VOCs were detected more frequently in wells located in heavily urbanized areas. The number of VOCs detected in ground water was positively correlated to the degree of urbanization. VOCs are produced and used primarily in urban land use settings; therefore, aquifers underlying urban areas may be more susceptible to contamination from these compounds.

Other variables had little or no predictability. Overall, the presence of high nitrate concentrations was only marginally useful in predicting aquifer susceptibility to VOC contamination. In Fresno, nitrate concentrations had a moderate correlation to VOC occurrence in ground water, whereas in Modesto, nitrate concentrations did not predict VOC occurrence. The density of LUFTs and the stable isotopic content of ground water were not good predictors of VOC occurrence in Fresno and Modesto ground water. LUFT density was not useful because gasoline components comprised less than 2 percent of the VOCs detected in the study areas. Source of recharge water is indicated by stable isotope ratios. The presence or absence of VOCs in ground-water samples was not correlated with stable isotope values. Therefore, source of recharge water was not important in predicting aquifer susceptibility in the Fresno and Modesto study areas.

September 22, 2004

OFR 2004-1296. COLORADO.

A Summary of the Scientific Literature on the Effects of Fire on the Concentration of Nutrients in Surface Waters. By Anthony J. Ranalli, pages.

Available on line.

This paper provides a detailed review of the chemical changes that occur in soil during a fire, the pathways by which nutrients are transferred from soil to surface-water bodies following a fire, and the temporal and spatial effects of fires on the concentration of nutrients in surface-water bodies during and following a fire that have been reported in the scientific literature. Thirty-nine papers from the scientific literature that represent studies that (1) were done in a variety of environments (savannas, grasslands, temperate forests, alpine forests, and so forth); (2) had a range of sampling frequency and duration, such as during and immediately following a fire (from the start of fire to 1 year later), short-term sampling (from end of fire to 3 years later), and long term-sampling (sampling for greater than 3 years following a fire); and (3) incorporated watersheds with various burn intensities, severities, and histories were reviewed and summarized. The review of the scientific literature has revealed that measurable effects of fires on streamwater quality are most likely to occur if the fire was severe enough to burn large amounts of organic matter, if windy conditions were present during the fire, if heavy rain occurred following the fire, and if the fire occurred in a watershed with steep slopes and soils with little cation-exchange capacity. Measurable effects of fires on lake- and reservoir-water quality are most likely to occur if, in addition to the factors listed for streams, the lake or reservoir is oligotrophic or mesotrophic and the residence time of water in the lake or reservoir is short relative to the length of time elevated concentrations of nutrients occur in runoff. Knowledge of whether a lake or reservoir is nitrogen or phosphorus limited is important because eutrophication of nitrogen-limited lakes may occur following a fire due to increasing nitrogen:phosphorus ratios caused by prolonged increases of nitrogen concentrations, especially nitrate.

September 17, 2004

OFR 2004-1308. NORTH DAKOTA, MINNESOTA, SOUTH DAKOTA.

Water-Use Data for the Red River of the North Basin, North Dakota, Minnesota, and South Dakota, 1979-2001. By Macek-Rowland, K.M., Arntson, A.D., Ryberg, K.R., Dahl, A.L., Lieb, A, 255 pages.

Available on line.

The Red River of the North, located in the north-central plains of the United States, plays an important role in population growth and economic development of the region. Because of recent and projected growth in population, industry, and agriculture in the Red River of the North Basin, alternatives to additional water resources will be needed to supplement future water needs. Past and current water-use data are needed to help select the most viable water-resource alternatives. Withdrawal and return flow data were collected from various sources throughout the Red River of the North Basin from 1979 through 2001. The withdrawal data were aggregated by subbasin, monthly totals, and water-use categories. The return flow data were aggregated by subbasin and monthly totals. The Red River of the North Basin was divided into subbasins based on locations of U.S. Geological Survey streamflow-gaging stations and by specifically-identified reaches. Results of the water-use compilation are provided in this report.

September 14, 2004

On-Line only

Available on line.

This report contains pesticide concentration data for water, and suspended and bed sediment samples collected in April 2003 from twelve sites along the New and Alamo Rivers in the Salton Sea watershed, in southeastern California. The study was done in collaboration with the California State Regional Water Quality Control Board, Colorado River Region, to assess inputs of current-use pesticides associated with water and sediment into the New and Alamo Rivers. Five sites along the New River and seven sites along the Alamo River, downstream of major agricultural drains, were selected and covered the lengths of the rivers from the international boundary to approximately 1.5 km from the river mouths. Sampling from bridges occurred at seven of the twelve sites. At these sites, streamflow measurements were taken. These same sites were also characterized for cross-stream homogeneity by measuring dissolved oxygen, pH, specific conductance, temperature, and suspended solids concentration at several vertical (depths) and horizontal (cross-stream) points across the river.

    Large volume water samples (200.300 L) were collected for isolation of suspended sediments by flow-through centrifugation. Water from the outflow of the flow-through centrifuge was sampled for the determination of aqueous pesticide concentrations. In addition, bottom sediments were sampled at each site. Current-use pesticides and legacy organochlorine compounds (p,p´-DDT, p,p´-DDE and p,p´-DDD) were extracted from sediments and measured via gas chromatography/mass spectrometry (GC/MS). Organic carbon and percentage of fines were also determined for suspended and bottom sediments. 
    Cross-stream transects of dissolved constituents and suspended sediments showed that the rivers were fairly homogeneous at the sites sampled. Streamflow was higher at the outlet sites, with the Alamo River having higher flow (1,240 cfs) than the New River (798 cfs).
    Twelve current-use pesticides, one legacy organochlorine compound (p,p´-DDE), and the additive piperonyl butoxide were detected in water samples. Trifluralin was found in the highest concentration of all detected compounds (68.5.599 ng/L) at all sites in both rivers, except for the international boundary sites. Atrazine was also detected in high concentration (51.0.285 ng/L) at several sites. The outlet sites had among the highest numbers of pesticides detected and the international boundary sites had the lowest numbers of pesticides detected for both rivers. The numbers of pesticides detected were greater for the Alamo River than for the New River.
    Six current-use pesticides and two legacy organochlorines (p,p´-DDE and p,p´-DDD) were found associated with suspended and bed sediments. The DDT metabolite p,p´-DDE was detected in all suspended and bed sediments from the Alamo River, but only at two sites in the New River. Dacthal, chlorpyrifos, pendimethalin, and trifluralin were the most commonly detected current-use pesticides. Trifluralin was the compound found in the highest concentrations in suspended (14.5.120 ng/g) and bed (1.9.9.0 ng/g) sediments. The sites along the Alamo River had more frequent detections of pesticides in suspended and bed sediments when compared with the New River sites. The greatest number of pesticides that were detected in suspended sediments (seven) were in the samples from the Sinclair Road and Harris Road sites. For bottom sediments, the Alamo River outlet site had the greatest number of pesticide detections (eight).

September 13, 2004

SIR 2004-5009. PENNSYLVANIA.

Available on line.

This report presents the results of a study by the Allegheny County Health Department (ACHD) and the U.S. Geological Survey (USGS) to determine the concentrations of fecal-indicator bacteria in the Allegheny, Monongahela, and Ohio Rivers (Three Rivers) in Allegheny County, Pittsburgh, Pa. Water-quality samples and river-discharge measurements were collected from July to September 2001 during dry- (72-hour dry antecedent period), mixed-, and wet-weather (48-hour dry antecedent period and at least 0.3 inch of rain in a 6-hour period) conditions at five sampling sites on the Three Rivers in Allegheny County. Water samples were collected weekly to establish baseline conditions and during successive days after three wet-weather events.

Water samples were analyzed for fecal-indicator organisms including fecal-coliform (FC) bacteria, Escherichia coli (E. coli), and enterococci bacteria. Water samples were collected by the USGS and analyzed by the ACHD Laboratory. At each site, left-bank and right-bank surface-water samples were collected in addition to a composite sample (discharge-weighted sample representative of the channel cross section as a whole) at each site. Fecal-indicator bacteria reported in bank and composite samples were used to evaluate the distribution and mixing of bacteria-source streams in receiving waters such as the Three Rivers.

Single-event concentrations of enterococci, E. coli, and FC during dry-weather events were greater than State and Federal water-quality standards (WQS) in 11, 28, and 28 percent of the samples, respectively; during mixed-weather events, concentrations of fecal-indicator bacteria were greater than WQS in 28, 37, and 43 percent of the samples, respectively; and during wet-weather events, concentrations of fecal-indicator bacteria were greater than WQS in 56, 71, and 81 percent of samples, respectively.

Single-event, wet-weather concentrations exceeded those during dry-weather events for all sites except the Allegheny River at Oakmont. For this site, dilution during wet-weather events or the lack of source streams upgradient of the site may have caused this anomaly. Additionally, single-event concentrations of E. coli and FC frequently exceeded the WQS reported during wet-weather events.

It is difficult to establish a short-term trend in fecal-indicator bacteria concentrations as a function of time after a wet-weather event due to factors including the spatial variability of sources contributing fecal material, dry-weather discharges, resuspension of bottom sediments, and flow augmentation from reservoirs. Relative to E. coli and enterococci, FC concentrations appeared to decrease with time, which may be attributed to the greater die-off rate for FC bacteria.

Fecal-indicator bacteria concentrations at a site are dependent on the spatial distribution of point sources upstream of the station, the time-of-travel, rate of decay, and the degree of mixing and resuspension. Therefore, it is difficult to evaluate whether the left, right, and composite concentrations reported at a particular site are significantly different. To evaluate the significance of the fecal-indicator bacteria concentrations and turbidity reported in grab and composite samples during dry-, mixed-, and wet-weather events, data sets were evaluated using Wilcoxon rank sum tests. Tests were conducted using the fecal-indicator bacteria colonies and turbidity reported for each station for a given weather event. For example, fecal coliform counts reported in the left-bank sample were compared against the right-bank and composite samples, respectively, for the Ohio River at Sewickley site during dry-, mixed-, and wet-weather events.

The statistical analyses suggest that, depending on the sampling site, the fecal-bacteria concentrations measured at selected locations vary spatially within a channel (left bank compared to right, right bank compared to composite). The most significant differences occurred between fecal-indicator bacteria in the left bank compared to composite and right bank compared to composite samples (p-values = 0.003 to 0.1), suggesting that during some wet- and dry-weather events, the mixing of source streams and the receiving water is incomplete. Turbidity (p-values = 0.003 to 0.1) and enterococci (p-values = 0.007 to 0.02) most frequently demonstrated a correlation between sample locations (left bank versus composite). Correlations between left-bank and right-bank samples were rare.

September 10, 2004

On-line only

Available on line.

The Velocity Profile Viewer (VPV) is a tool for visualizing time series of velocity profiles developed by the U.S. Geological Survey (USGS). The USGS uses VPV to preview and present measured velocity data from acoustic Doppler current profilers and simulated velocity data from three-dimensional profile or as a stack of time-series graphs that each represents a location in the water column. The graphically displayed data are shown at each time step like frames of animation. The animation can play at several different speeds or can be suspended on one frame. The viewing angle and time can be manipulated using mouse interaction. A number of options control the appearance of the profile and the graphs. VPV cannot edit or save data, but it can create a Post-Script file showing the velocity profile in three dimensions. This user manual describes how to use each of these features. VPV is available to be downloaded for free from the World Wide Web at http://ca.water.usgs.gov/program/sfbay/vpv

September 9, 2004

SIR 2004-5111.

Available from U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5111, 18 p., 3 fig.

Streambed scour at bridge piers is among the leading causes of bridge failure in the United States. Several pier-scour equations have been developed to calculate potential scour depths at existing and proposed bridges. Because many pier-scour equations are based on data from laboratory flumes and from cohesionless silt- and sand-bottomed streams, they tend to overestimate scour for piers in coarse-bed materials. Several equations have been developed to incorporate the mitigating effects of large particle sizes on pier scour, but further investigations are needed to evaluate how accurately pier-scour depths calculated by these equations match measured field data.

This report, prepared in cooperation with the Montana Department of Transportation, describes the evaluation of five pier-scour equations for coarse-bed streams. Pier-scour and associated bridge-geometry, bed-material, and streamflow-measurement data at bridges over coarse-bed streams in Montana, Alaska, Maryland, Ohio, and Virginia were selected from the Bridge Scour Data Management System. Pier scour calculated using the Simplified Chinese equation, the Froehlich equation, the Froehlich design equation, the HEC-18/Jones equation, and the HEC-18/Mueller equation for flood events with approximate recurrence intervals of less than 2 to 100 years were compared to 42 pier-scour measurements. Comparison of results showed that pier-scour depths calculated with the HEC-18/Mueller equation were seldom smaller than measured pier-scour depths. In addition, pier-scour depths calculated using the HEC-18/Mueller equation were closer to measured scour than for the other equations that did not underestimate pier scour. However, more data are needed from coarse-bed streams and from less frequent flood events to further evaluate pier-scour equations.

August 25, 2004

other 2004-5117. CALIFORNIA.

Occurrence, Distribution, and Transport of Pesticides, Trace Elements, and Selected Inorganic Constituents into the Salton Sea Basin, California, 2001−2002. By Lawrence A. LeBlanc, Roy .A. Schroeder, James L. Orlando, and Kathryn M. Kuivila , 40 pages.

Available on-line only.

A study of pesticide distribution and transport within the Salton Sea Basin, California, was conducted from September 2001 to October 2002. Sampling for the study was done along transects for the three major rivers that flow into the Salton Sea Basin: the New and Alamo Rivers at the southern end of the basin and the Whitewater River at the northern end. Three stations were established on each river: an outlet station approximately 1 mile upstream of the river discharge, a near-shore station in the river delta, and off-shore station in the Salton Sea. Water and suspended and bed sediments were collected at each station in October 2001, March−April 2002, and September 2002, coinciding with peak pesticide applications in the fall and spring. Fourteen current-use pesticides were detected in the water column. Concentrations of dissolved pesticides typically decreased from the outlets to the sea in all three rivers, consistent with the off-shore transport of pesticides from the rivers to the sea. Dissolved concentrations ranged from the limits of detection to 151 nanograms per liter (ng/L); however, diazinon, eptam (EPTC), and malathion were detected at much higher concentrations (940.3,830 ng/L) at the New and Alamo River outlet and near-shore stations. Concentrations of carbaryl, dacthal, diazinon, and eptam were higher during the two fall sampling periods, whereas concentrations of atrazine, carbofuran, and trifluralin were higher during the spring. Current-use pesticides also were detected on suspended and bed sediments in concentrations ranging from method detection limits to 106 ng/g (nanograms per gram). Chlorpyrifos, dacthal, eptam, trifluralin, and DDE were the most frequently detected pesticides on sediments from all three rivers. The number and concentrations of pesticides associated with suspended sediments frequently were similar for the river outlet and near-shore sites, consistent with the downstream transport of sediment-associated pesticides out of the rivers. Seasonal trends in pesticide concentration were similar to those for dissolved concentrations in fall 2001 and spring 2002, but not in fall 2002. Generally, the pesticides detected in the suspended sediments were the same pesticides detected in the bed sediments, and concentrations were similar, especially at the Alamo River outlet site in spring 2002 and fall 2002. Pesticides generally were not detected in sediments from the off-shore sites; however, the samples from these sites also had greater incidences of matrix interference during analysis. Sediment-associated pesticide concentrations were above equilibrium in water, suggesting a bound fraction of sediment-associated pesticides that are resistant to desorption. Concentrations of trace elements and other inorganic constituents in suspended sediments collected during the fall 2001 followed expected trends with dilution of river-derived minerals owing to highly organic autochthonous production within the Salton Sea Basin. However, calculation of enrichment ratios provided evidence for the bioconcentration of several trace elements, notably selenium in the off-shore biota.

August 23, 2004

SIR 2004-5040. TENNESSEE.

Hydrogeology and Ground-Water-Flow Simulation in the Former Airfield Area of Naval Support Activity Mid-South, Millington, Tennessee. By Connor J. Haugh, John K. Carmichael, and David E. Ladd, 31 pages.

U.S. Geological Survey, Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5040, 31 p., 19 figs.

Naval Support Activity Mid-South is a Department of the Navy base located in Millington, Tennessee. The facility was home to the Naval Aviation Technical Training Center from 1943 until 1996. As part of the Base Closure and Realignment Act of 1990, the primary training mission of the facility was realigned and most of the northern part of the base, referred to as the Northside and consisting primarily of an airfield, was transferred to the city of Millington in January 2000. During environmental investigations at the base, plumes of dissolved chlorinated solvents resulting from past aircraft maintenance and training operations were identified in shallow ground water beneath the airfield area. The airfield area containing the plumes has been designated as Area of Concern (AOC) A. Chlorinated solvents, primarily trichloroethene (TCE), are the principal contaminants in ground water at AOC A, with TCE identified in concentrations as high as 4,400 micrograms per liter. The nature and extent of these plumes at AOC A were addressed during a Resource Conservation and Recovery Act Facility Investigation, and selected options for remediation currently are being implemented under a corrective action program. As part of these efforts, the U.S. Geological Survey (USGS) is working with the Navy and its consultants to study the hydrogeologic framework of the base and surrounding area, with a focus on AOC A.

Since 1997, investigations at and near the facility have produced data prompting revisions and additions to information published that year in two USGS reports. The updates are presented in this report and consist primarily of (1) refinements to selected hydrogeologic maps presented in the 1997 reports, on the basis of data collected from new wells at on- and off-base locations, (2) additional hydraulic-conductivity data collected for the alluvial-fluvial deposits aquifer at AOC A, and (3) construction of a potentiometric-surface map of the shallow aquifer for the former part of the Naval Support Activity Mid-South Northside and adjacent off-base locations for February and March 2000 water-level conditions. Additionally, a numerical ground-water-flow model of AOC A was developed and calibrated to the February and March 2000 potentiometric-surface data, the results of which also are presented in this report. Particle-tracking simulations were used with the model to simulate ground-water-flow paths from two sites suspected of being contaminant source areas at AOC A. The flow paths indicated by the particle tracking simulations agree reasonably well with maps of the interpreted extents of TCE plumes. The time-of-travel plots show that advective travel times from the two suspected source areas to the model boundary are controlled by relative proximities of the source areas to a part of AOC A identified from investigations and simulated with the model as having the highest horizontal hydraulic conductivity.

August 19, 2004

SIR 2004-5094. CONNECTICUT.

Analysis of Phosphorus Trends and Evaluation of Sampling Designs in the Quinebaug River Basin, Connecticut. By Elaine C. Todd Trench, 18 pages.

Available from the USGS Connecticut District Office, 101 Pitkin St., East Hartford, CT 06108 (phone 860-291-6740) and at the USGS libraries in Reston, Va., Denver, Colo., and Menlo Park, Calif., U.S. Geological USGS Scientific Investigations Report 2004-5094, 18 p., 9 figs.

A time-series analysis approach developed by the U.S. Geological Survey was used to analyze trends in total phosphorus and evaluate optimal sampling designs for future trend detection, using long-term data for two water-quality monitoring stations on the Quinebaug River in eastern Connecticut. Trend-analysis results for selected periods of record during 1971-2001 indicate that concentrations of total phosphorus in the Quinebaug River have varied over time, but have decreased significantly since the 1970s and 1980s. Total phosphorus concentrations at both stations increased in the late 1990s and early 2000s, but were still substantially lower than historical levels. Drainage areas for both stations are primarily forested, but water quality at both stations is affected by point discharges from municipal wastewater-treatment facilities.

Various designs with sampling frequencies ranging from 4 to 11 samples per year were compared to the trend-detection power of the monthly (12-sample) design to determine the most efficient configuration of months to sample for a given annual sampling frequency. Results from this evaluation indicate that the current (2004) 8-sample schedule for the two Quinebaug stations, with monthly sampling from May to September and bi-monthly sampling for the remainder of the year, is not the most efficient 8-sample design for future detection of trends in total phosphorus. Optimal sampling schedules for the two stations differ, but in both cases, trend-detection power generally is greater among 8-sample designs that include monthly sampling in fall and winter. Sampling designs with fewer than 8 samples per year generally provide a low level of probability for detection of trends in total phosphorus.

Managers may determine an acceptable level of probability for trend detection within the context of the multiple objectives of the state's water-quality management program and the scientific understanding of the watersheds in question. Managers may identify a threshold of probability for trend detection that is high enough to justify the agency.s investment in the water-quality sampling program. Results from an analysis of optimal sampling designs can provide an important component of information for the decision-making process in which sampling schedules are periodically reviewed and revised.

Results from the study described in this report and previous studies indicate that optimal sampling schedules for trend detection may differ substantially for different stations and constituents. A more comprehensive statewide evaluation of sampling schedules for key stations and constituents could provide useful information for any redesign of the schedule for water-quality monitoring in the Quinebaug River Basin and elsewhere in the state.

August 10, 2004

other Techniques and Methods 4-4A.

Guidelines for Preparation of State Water-Use Estimates for 2000. By Joan F. Kenny, 49 pages.
/

Available on line.

This report describes the water-use categories and data elements required for the 2000 national water-use compilation conducted by the U.S. Geological Survey (USGS) as part of its National Water Use Information Program. It identifies sources of water-use information, guidelines for estimating water use, and required documentation for preparation of the national compilation by State for the United States, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands. The data are published in USGS Circular 1268, Estimated Use of Water in the United States in 2000. USGS has published circulars on estimated use of water in the United States at 5-year intervals since 1950.

As part of this USGS program to document water use on a national scale for the year 2000, all States prepare estimates of water withdrawals for public supply, industrial, irrigation, and thermoelectric power generation water uses at the county level. All States prepare estimates of domestifc use and population served by public supply at least at the State level. All States provide estimates of irrigated acres by irrigation system type (sprinkler, surface, or microirrigation) at the county level. County-level estimates of withdrawals for mining, livestock, and aquaculture uses are compiled by selected States that comprised the largest percentage of national use in 1995 for these categories, and are optional for other States. Ground-water withdrawals for public-supply, industrial, and irrigation use are aggregated by principal aquifer or aquifer system, as identified by the USGS Office of Ground Water.

Some categories and data elements that were mandatory in previous compilations are optional for the 2000 compilation, in response to budget considerations at the State level. Optional categories are commercial, hydroelectric, and wastewater treatment. Estimation of deliveries from public supply to domestic, commercial, industrial, and thermoelectric uses, consumptive use for any category, and irrigation conveyance loss are optional data elements. Aggregation of data by the eight-digit hydrologic cataloging unit is optional.

Water-use data compiled by the States are stored in the USGS Aggregated Water-Use Data System (AWUDS). This database is designed to store both mandatory and optional data elements. AWUDS contains several routines that can be used for quality assurance and quality control of the data, and also produces tables of water-use data compiled for 1985, 1990, 1995, and 2000. These water-use data are used by USGS, other agencies, organizations, academic institutions, and the public for research, water-management decisions, trend analysis, and forecasting.

August 10. 2004

other Data Series 88.

Acetamide herbicides and their degradation products in ground water and surface water of the United States, 1993-2003. By Elisabeth A. Scribner, Julie E. Dietze, and E. Michael Thurman, 252 pages.

U.S. Geological Survey
Information Services
Building 810, Denver Federal Center
Denver, CO 80225

Available on line.

During 1993 through 2003, the U.S. Geological Survey conducted a number of studies to investigate and document the occurrence, fate, and transport of acetamide herbicides and their degradation products in ground and surface water. As part of these studies, approximately 5,100 water samples were collected and analyzed for the acetamide parent herbicides acetochlor, alachlor, dimethenamid, flufenacet, and metolachlor and their degradation products ethanesulfonic acid, oxanilic acid, and sulfinyl acetic acid. During this period, various analytical methods were developed to detect and measure concentrations of acetamide herbicides and their degradation products in ground water and surface water. Results showed that the degradation products of acetamide herbicides in ground water were detected more frequently and occurred at higher concentrations than their parent compounds. Further study showed that the acetamide herbicides and their degradation products were detected more frequently in surface water than in ground water. In general, the parent compounds were detected at similar or greater frequencies than the degradation products in surface water. The developed methods and data were valuable for acquiring information about the occurrence, fate, and transport of the herbicides and their degradation products and the importance of analyzing for both parent compounds and their degradate products in water-quality studies.

August 9, 2004

OFR 03-499. PENNSYLVANIA.

Assessment of water chemistry, habitat, and benthic macroinvertebrates at selected stream-quality monitoring sites in Chester County, Pennsylvania, 1998-2000. By Andrew G. Reif, 84 pages.

Available from the USGS Pa. District ofice, 215 Limekiln Road, New Cumberland, PA 17070 (phone 717-730-6900) and at the USGS libraries in Reston, Va., Denver, Colo., and Menlo Park, Calif., U.S. Geological Open-File Report 03-499, 84 p., 36 figs.

Available on line.

Biological, chemical, and habitat data have been collected from a network of sites in Chester County, Pa., from 1970 to 2003 to assess stream quality. Forty sites in 6 major stream basins were sampled between 1998 and 2000. Biological data were used to determine levels of impairment in the benthic-macroinvertebrate community in Chester County streams and relate the impairment, in conjunction with chemical and habitat data, to overall stream quality. Biological data consisted of benthic-macroinvertebrate samples that were collected annually in the fall. Water-chemistry samples were collected and instream habitat was assessed in support of the biological sampling.

Most sites in the network were designated as nonimpacted or slightly impacted by human activities or extreme climatic conditions on the basis of biological-metric analysis of benthic-macroinvertebrate data. Impacted sites were affected by factors, such as nutrient enrichment, erosion and sedimentation, point discharges, and droughts and floods. Streams in the Schuylkill River, Delaware River, and East Branch Brandywine Creek Basins in Chester County generally had low nutrient concentrations, except in areas affected by wastewater-treatment discharges, and stream habitat that was affected by erosion. Streams in the West Branch Brandywine, Christina, Big Elk, and Octoraro Creek Basins in Chester County generally had elevated nutrient concentrations and stream-bottom habitat that was affected by sediment deposition.

Macroinvertebrate communities identified in samples from French Creek, Pigeon Creek (Schuylkill River Basin), and East Branch Brandywine Creek at Glenmoore consistently indicate good stream conditions and were the best conditions measured in the network. Macroinvertebrate communities identified in samples from Trout Creek (site 61), West Branch Red Clay Creek (site 55) (Christina River Basin), and Valley Creek near Atglen (site 34) (Octoraro Creek Basin) indicated fair to poor stream conditions and were the worst conditions measured in the network. Trout Creek is heavily impacted due to erosion, and Valley Creek near Atglen and West Branch Red Clay Creek are influenced by wastewater discharges.

Hydrologic conditions in 1999, including a prolonged drought and a flood, influenced chemical concentrations and macroinvertebrate community structure throughout the county. Concentra-tions of nutrients and ions were lower in 1999 when compared to 1998 and 2000 concentrations. Macroinvertebrate communities identified in samples from 1999 contained lower numbers of individuals when compared to 1998 and 2000 but had similar community structure. Results from chemical and biological sampling in 2000 indicated that the benthic-macroinvertebrate community structure and the concentrations of nutrients and ions recovered to pre-1999 levels.

August 2, 2004

WRI 03-4324. IDAHO.

Characterization of Channel Substrate, and Changes in Suspended-Sediment Transport and Channel Geometry in White Sturgeon Spawning Habitat in the Kootenai River near Bonners Ferry, Idaho, Following the Closure of Libby Dam. By Barton, Gary J, 102 pages.

ONLY available online

Many local, State, and Federal agencies have concerns over the declining population of white sturgeon (Acipenser transmontanus) in the Kootenai River and the possible effects of the closure and subsequent operation of Libby Dam in 1972. In 1994, the Kootenai River white sturgeon was listed as an Endangered Species. A year-long field study was conducted in cooperation with the Kootenai Tribe of Idaho along a 21.7-kilometer reach of the Kootenai River including the white sturgeon spawning reach near Bonners Ferry, Idaho, approximately 111 to 129 kilometers below Libby Dam. During the field study, data were collected in order to map the channel substrate in the white sturgeon spawning reach. These data include seismic subbottom profiles at 18 cross sections of the river and sediment cores taken at or near the seismic cross sections. The effect that Libby Dam has on the Kootenai River white sturgeon spawning substrate was analyzed in terms of changes in suspended-sediment transport, aggradation and degradation of channel bed, and changes in the particle size of bed material with depth below the riverbed.

The annual suspended-sediment load leaving the Kootenai River white sturgeon spawning reach decreased dramatically after the closure of Libby Dam in 1972: mean annual pre-Libby Dam load during 1966-71 was 1,743,900 metric tons, and the dam-era load during 1973-83 was 287,500 metric tons. The amount of sand-size particles in three suspended-sediment samples collected at Copeland, Idaho, 159 kilometers below Libby Dam, during spring and early summer high flows after the closure of Libby Dam is less than in four samples collected during the pre-Libby Dam era. The supply of sand to the spawning reach is currently less due to the reduction of high flows and a lossof 70 percent of the basin after the closure of Libby Dam.

The river's reduced capacity to transport sand out of the spawning reach is compensated to an unknown extent by a reduced load of sand entering the spawning reach. Since the closure of Libby Dam, the most notable change in channel geometry at the Copeland streamflowgaging station was the initiation of cyclical aggradation and degradation of the riverbed in the center of the channel.

The aggradation and degradation of the riverbed are reflected in a twofold increase, from 1.3 to 2.5 meters, in the fluctuation of the minimum riverbed elevation, which suggests that during the Libby Dam era, parts of the riverbed in the spawning reach may have aggraded or degraded by as much as 2.5 meters.

Before the closure of Libby Dam, there was a greater propensity for aggradation and degradation of sand over the discontinuous gravel and cobble layers in the buried gravelcobble reach at Bonners Ferry. The gravel and cobble in this reach, 111.3 to 115.9 kilometers below Libby Dam, are buried by sand. Unregulated spring snowmelt-runoff flows flushed part of the sand layer and exposed some of the buried gravel-cobble layer because streamflow velocities were higher at that time. Unregulated autumn-winter baseflows gradually deposited silt and sand and reestablished a sand layer, burying the gravel-cobble layer. This cyclical process of aggradation and degradation of the riverbed sediment is reflected in the alternating gravel-cobble layers and sand layers found in sediment core K18-TH taken as part of this project.

White sturgeon spawning substrate in the Kootenai River meander reach is currently composed of alluvial sand that forms sand dunes and of minor amounts of lacustrine clay and silt that generally are found in the river's thalweg.

The present substrate composition in the meander reach is considered similar to that which existed prior to closure of Libby Dam, with one possible exception. Prior to closure of Libby Dam, minor amounts of gravel and cobble may have been exposed on the riverbed in the spawning reach just below the mouth of Myrtle Creek 230 kilometers below Libby Dam. The substrate composition near Shorty Island, 234 kilometers below Libby Dam, a notable white sturgeon spawning reach, is predominantly sand and is similar to that which existed prior to closure of Libby Dam.

August 2, 2004

SIR 2004-5083. CALIFORNIA.

Occurrence, Distribution, Instantaneous Loads, and Yields of Dissolved Pesticides in the San Joaquin River Basin, California, During Summer Conditions, 1994 and 2001. By Larry R. Brown, Sandra Y. Panshin, Charles R. Kratzer, Celia Zamora, and JoAnn M. Gronberg, 53 pages.

Available on line.

Water samples were collected from 22 drainage basins for analysis of 48 dissolved pesticides during summer flow conditions in 1994 and 2001. Of the 48 pesticides, 31 were reported applied in the basin in the 28 days preceding the June 1994 sampling, 25 in the 28 days preceding the June 2001 sampling, and 24 in the 28 days preceding the August 2001 sampling. The number of dissolved pesticides detected was similar among sampling periods: 26 were detected in June 1994, 28 in June 2001, and 27 in August 2001. Concentrations of chlorpyrifos exceeded the California criterion for the protection of aquatic life from acute exposure at six sites in June 1994 and at five sites in June 2001. There was a single exceedance of the criterion for diazinon in June 1994. The number of pesticides applied in tributary basins was highly correlated with basin area during each sampling period (Spearman's r = 0.85, 0.70, and 0.84 in June 1994, June 2001, and August 2001, respectively, and p < 0.01 in all cases). Larger areas likely include a wider variety of crops, resulting in more varied pesticide use. Jaccard's similarities, cluster analysis, principal components analysis, and instantaneous load calculations generally indicate that west-side tributary basins were different from east-side tributary basins. In general, west-side basins had higher concentrations, instantaneous loads, and instantaneous yields of dissolved pesticides than east-side basins, although there were a number of exceptions. These differences may be related to a number of factors, including differences in basin size, soil texture, land use, irrigation practices, and stream discharge.

July 29, 2004

Available from the U.S. Geological Survey, Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5074, 33 p., 14 figs.

The Quail Hollow Landfill, located in southeastern Bedford County on the Highland Rim overlooking the Central Basin karst region of Tennessee, is constructed on the gravelly, clay-rich residuum of the Fort Payne Formation of Mississippian age. A conceptual hydrologic model of the landfill indicated that Anderton Branch was at risk of being affected by the landfill. Ground water flowing beneath the landfill mixes with percolating rainwater that has passed through the landfill and discharges to the surface from numerous weeps, seeps, and springs present in the area. Anderton Branch, adjacent to the landfill site on the north and east, receives most of the discharge from these weeps, seeps, and springs. Anderton Branch also receives water from the Powell Branch drainage basin to the west and south because of diverted flow of ground water through Harrison Spring Cave. The U.S. Geological Survey, in cooperation with the Bedford County Solid Waste Authority, conducted a study to evaluate the effect of the Quail Hollow Landfill on ground- and surface-water quality.

During storm runoff, specific conductance was elevated, and cadmium, iron, manganese, lead, and nickel concentrations in Anderton Branch frequently exceeded maximum contaminant levels for drinking water for the State of Tennessee. High chloride inputs to Anderton Branch were detected at two locations--a barnyard straddling the stream and a tributary draining a pond that receives water directly from the landfill. The chloride inputs probably contribute to chloride load levels that are three times higher for Anderton Branch than for the control stream Anthony Branch. Although toxic volatile organic compounds were detected in water from monitoring wells at the landfill, no organic contaminants were detected in domestic water wells adjacent to the landfill or in Anderton Branch.

Sons Spring, a karst spring near the landfill, has been affected by the landfill as indicated by an increase in chloride concentrations from 4 milligrams per liter in 1974 to 59 milligrams per liter in 1996. Analysis of water samples from Sons Spring detected concentrations of nickel that exceeded primary drinking-water standards and Tennessee Department of Environment and Conservation fish and aquatic life chronic standards. Trichloroethene, 1,1-dichloroethene, and 1,1-dichloroethane also were detected at Sons Spring. The presence of these chlorinated solvents imply the landfill origin of the contaminants in Sons Spring. Continuous monitoring at Sons Spring indicated a pattern of decreased specific conductance and lower contaminant concentrations after a storm. Contaminant concentrations increased with specific conductance to pre-storm levels after several days.

The benthic macroinvertebrate community in Anderton Branch adjacent to the landfill was not different from the communities at control sites upstream and in Anthony Branch. Sons Spring, however, has low abundance and numbers of benthic macroinvertebrate taxa. Toxicity studies using Ceriodaphnia dubia indicated no toxicity in the base flow or storm water in Anderton Branch or in a tributary draining a pond that receives water from the landfill and Sons Spring; however, water collected from Sons Spring resulted in 100 percent mortality to all organisms within 48 hours.

High concentrations of nickel were detected in crayfish tissue from control sites and Anderton Branch. Analysis of sediment samples also indicates nickel concentrations are high at control sites upstream of the landfill. Increased levels of the biomarker metallothionein detected in crayfish from Anderton Branch likely are not caused by nickel or cadmium because the levels present in the tissue are not correlated with metallothionein levels.

Despite the high levels of certain metals in Anderton Branch during storm flow, the lack of toxicity and the health of the benthic community imply no detectable negative effect from the landfill to the stream. Sons Spring, however, is toxic and almost devoid of organisms. A high chloride concentration in the water from Brinkley tributary indicates the landfill as the origin of this water; however, the lack of contamination and toxicity in this water imply that biologic activity and filtering occurring in Brinkley Pond is improving the water quality. The overall negative effect from landfill-contaminated water appears to be localized to the area in the immediate vicinity of Sons Spring and in short reaches of Anderton Branch adjacent to the landfill.

July 29, 2004

Available from U.S. Geological Survey Information Services, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS WRIR 03-4131.

Chemical and is otopic data were obtained from ground water and surface water throughout t he Middle Rio Grande Basin (MRGB), New Mexico, and supplemented with selec ted data from the U.S. Geological Survey (USGS) National Water Information System (NWIS) and City of Albuquerque water-quality database in an effor t to refine the conceptual model of ground-water flow in the basin. The g round-water data collected as part of this study include major- and minor-element chemistry (30 elements), oxygen-18 and deuterium content of water, carbon-13 content and carbon-14 activity of dissolved inorganic carbon, sulfur-34 content of dissolved sulfate, tritium, and dissolved atmospheric gases including nitrogen, argon, helium, chlorofluorocarbons, and sulfur hexafluoride from 288 wells and springs in parts of the Santa Fe Group aquifer system. The surface-water data collected as part of this study include monthly measurements of major- and minor-element chemistry (30 elements), oxygen-18 and deuterium content of water, chlorofluorocarbons, and tritium content at 14 locations throughout the basin. Additional data include stable isotope analyses of precipitation and of ground water from City of Albuquerque production wells collected and archived from the early 1980.s, and other data on the chemical and isotopic composition of air, unsaturated zone air, plants, and carbonate minerals from throughout the basin.

The data were used to identify 12 sources of water to the basin, map spatial and vertical extents of ground-water flow, map water chemistry in relation to hydrogeologic, stratigraphic, and structural properties of the basin, determine radiocarbon ages of ground water, and reconstruct paleo-environmental conditions in the basin over the past 30,000 years.

The data indicate that concentrations of most elements and isotopes general ly parallel the predominant north to south direction of ground-water flow. The radiocarbon ages of dissolved inorganic carbon in ground water range from modern (post-1950) to more than 30,000 years before present, and appear to be particularly well defined in the predominantly siliciclastic aquifer system. Major sources of water to the basin include (1) recharge from mountains along the north, east, and southwest margins (median age 5,000-9,000 years); (2) seepage from the Rio Grande and Rio Puerco (median age 4,000-8,000 years) and from Abo and Tijeras Arroyos (median age 3,000-9,000 years); (3) inflow of saline water along the southwestern basin margin (median age 20,000 years); and (4) inflow along the northern basin margin that probably represents recharge from the Jemez Mountains during the last glacial period (median age 20,000 years). Water recharged from the Jemez Mountains during the last glacial period occurs at the water table in the central part of the basin and beneath younger recharge along the Rio Grande and the northern mountain front.

In some parts of the basin, boundaries between hydrochemical zones appear to be near major faults that may affect ground-water flow. However, in other parts of the basin, such as along the east side of Albuquerque near the Sandia Fault Zone, ground-water flow appears to be unaffected by major faults. Upward leakage of saline water occurs along some faults and can be a source of salinity and elevated arsenic concentrations in some ground water.

A trough in the modern and predevelopment water table west of Albuquerque is centered along a zone of predominantly late Pleistocene age water through the center of the basin and is flanked and overlain along the trough boundary by water that infiltrated from the Rio Puerco on the west and the Rio Grande to the east. It is suggested that the ground-water trough is a relatively recent transient feature of the Santa Fe Group aquifer system.

At Albuquerque, a distinct north-south boundary in deuterium content of ground water marks the division between recharge from the eastern mountain front and that from the Rio Grande. Water beneath approximately two-thirds of the City of Albuquerque is predominantly of Rio Grande origin infiltrated from areas north of the city.

The stable isotope data for ground water in the vicinity of Albuquerque indicate little movement of ground water in response to withdrawals from public supply wells during the past 20 years, even though in places the modern water table has fallen as much as 140 feet below the predevelopment potentiometric surface. Small shifts over the past 20 years in stable isotope composition of water discharged from public supply wells along the boundaries between the West-Central zone (paleowater) and Central zone (Rio Grande water) west of the Rio Grande, and along the boundary between the Central zone and Eastern Mountain Front zone east of the Rio Grande indicate local areas where paleowater of Rio Grande origin is beginning to move west and east in response to ground-water pumping.

Age gradients from piezometer nests range from 0.1 to 2 yr cm-1 and indicate a recharge rate of about 3 cm yr-1 for recharge along the eastern mountain front and infiltration from the Rio Grande near Albuquerque. There has been appreciably less recharge along the eastern mountain front in areas both north and south of Albuquerque.

The ä2H isotopic composition of water, and recharge temperatures based on dissolved N2 and Ar data, were interpreted in conjunction with the radiocarbon age to improve understanding of water source, and mechanism and timing of recharge. The N2-Ar recharge temperatures vary widely throughout the MRGB. The minimum recharge temperature for a particular hydrochemical zone appears to be near the mean annual temperature, and the maximum recharge temperature approaches that of ground water beneath the deep (greater than 300 feet) unsaturated zones. The dissolved gas recharge temperatures demonstrate cases of both focused (cold recharge temperatures) and diffuse flow (warm recharge temperatures) recharge mechanisms in the predominantly semiarid MRGB.

During the last glacial period, water recharged to the West-Central zone varied widely in stable isotope composition and recharge temperature, indicating the occurrence of both diffuse and focused recharge of low- and high-altitude precipitation. The range in delta 2H of West-Central zone waters from the last glacial maximum (LGM, approximately 18,000 radiocarbon years before present, B.P.), indicates recharge that occurred over a 4,000-foot range in altitude.

Ground water in the Central zone was recharged by direct infiltration from the Rio Grande and apparently records surface-water temperature and stable isotopic composition at the time of recharge. The dissolved N2-Ar data indicate that the average temperature of water infiltrated from the Rio Grande varied by only about ± 1 degree Celsius (deg C)from the modern mean annual temperature (13.6 deg C) at Albuquerque over the past 27,000 years. Rio Grande water was coldest (12.7 ± 1.4 deg C) during the period 15,000-27,000 years B.P., and warmest (14.5 ± 1.4 deg C) during the period 5,000-9,000 years B.P., and averaged 13.0 ± 2.2 deg C during the past 5,000 years. Together, the stable isotope data and dissolved gas recharge temperatures indicate that in the past, the timing of the spring runoff of northern New Mexico and southern Colorado snowmelt varied, coming late into early to mid-summer during cold periods and overlapping, in part, with the summer monsoon season (currently July-October). During warm periods, such as modern times, the peak discharge of the Rio Grande occurred in mid- to late spring in advance of the summer monsoon season. Recharge temperatures from approximately 20,000 radiocarbon years ago were as low as 3.2 deg C, as recorded in the dissolved gas composition of water recharged north of the basin, and 8.1 deg C along the eastern mountain front. During the last 5,000 years, the delta 2H isotopic composition of eastern mountain front recharge has decreased about 7 per mil. This decrease indicates an average cooling of about 1.4 deg C following the mid-Holocene warm period. Over the same time span, the delta 2H isotopic composition of Rio Grande water increased approximately 6 per mil, consistent with a shift in season of peak snowmelt into the beginning of the summer monsoon season.

The delta 13C isotopic composition of dissolved inorganic carbon in ground water is remarkably constant throughout most of the basin, indicating a nearly constant historical predominance of C4 over C3 plants. However, recent recharge along the basin margins indicates a rather abrupt increase in C3 plant abundance during the past 1,000 years, and perhaps even more recently than 1,000 years, as recorded in depleted delta 13C isotopic compositions of dissolved inorganic carbon (DIC).

This study demonstrates the benefits of obtaining a diverse and extensive chemical and isotopic dataset when characterizing hydrochemical processes in ground-water systems, retrieving historical environmental records from ground water, and/or refining conceptual models of ground-water systems.

July 29, 2004

Available on line.

The Owyhee River drains an extremely rugged and sparsely populated landscape in northern Nevada, southwestern Idaho, and eastern Oregon. Most of the segment between the Oregon State line and Lake Owyhee is part of the National Wild and Scenic Rivers System, and few water-quality data exist for evaluating environmental impacts. As a result, the U.S. Geological Survey, in cooperation with the Bureau of Land Management, assessed this river segment to characterize chemical and biological quality of the river, identify where designated beneficial uses are met and where changes in stream quality occur, and provide data needed to address activities related to environmental impact assessments and Total Maximum Daily Loads. Water-quality issues identified at one or more sites were water temperature, suspended sediment, dissolved oxygen, pH, nutrients, trace elements, fecal bacteria, benthic invertebrate communities, and periphyton communities. Generally, summer water temperatures routinely exceeded Oregon's maximum 7-day average criteria of 17.8 degrees Celsius. The presence of few coldwater taxa in benthic invertebrate communities supports this observation. Suspended-sediment concentrations during summer base flow were less than 10 milligrams per liter (mg/L). Dissolved solids concentrations ranged from 46 to 222 mg/L, were highest during base flow, and tended to increase in a downstream direction. Chemical compositions of water samples indicated that large proportions of upland-derived water extend to the lower reaches of the study area during spring runoff. Dissolved fluoride and arsenic concentrations were highest during base flow and may be a result of geothermal springs discharging to the river. No dissolved selenium was detected.

Upstream from the Rome area, spring runoff concentrations of suspended sediment ranged from 0 to 52 mg/L, and all except at the Three Forks site were typically below 20 mg/L. Stream-bottom materials from the North Fork Owyhee River, an area with no mines, were enriched with nine trace elements, which indicates that this basin may be a natural source of these elements.

Near Rome, the part of the study area not included in the National Wild and Scenic Rivers System, land-use impacts resulted in elevated populations of Escherichia coli bacteria (E. coli) during base flow and elevated concentrations of nitrogen and phosphorus during spring runoff. Sites in this area had the highest numbers of benthic invertebrates; the fewest Ephemeroptera, Plecoptera, and Trichoptera taxa; and the highest Hilsenhoff Biotic Index scores. These results suggest degraded stream quality. Periphyton communities at sites in this area approached nuisance levels and could cause significant dissolved oxygen depletions and pH values that exceed Oregon's recommended criteria. Stream-bottom materials from Jordan Creek were enriched with mercury and manganese, which probably were ultimately caused by past mining in that basin.

Below Crooked Creek, elevated suspended sediment concentrations (142 mg/L), phosphorus concentrations (0.23 mg/L), and E. coli populations (370 most probable number per 100 milliliters) during the largest spring runoff event could be the result of inputs at the lower end of Jordan Valley and (or) inputs from Crooked Creek. The New Zealand Mud Snail, a highly competitive gastropod introduced to the Snake River in the 1980s, was collected just downstream from the Crooked Creek confluence.

July 27, 2004

On-line Only

Available on line.

The effects of agriculture, particularly from the use of pesticides, on aquatic ecosystems in the San Joaquin River Basin concern many aquatic resource managers, water quality managers, and water users. A total of five sites were sampled once in June 2001 and once in September 2001 to document the periphyton (attached algae) community, the benthic macroinvertebrate (insects and non-insects) community, and stream habitat conditions. The purposes of the study were to document existing conditions and, to the extent possible, relate the periphyton and macroinvertebrate community condition to environmental conditions.

July 19, 2004

OFR 2004-1261.

MODFLOW-2000, The U.S. Geological Survey Modular Ground-Water Model--GMG Linear Equation Solver Package Documentation. By John D. Wilson and Richard L. Naff, 47 pages.

Available on line.

A geometric multigrid solver (GMG), based in the preconditioned conjugate gradient algorithm, has been developed for solving systems of equations resulting from applying the cell-centered finite difference algorithm to flow in porous media. This solver has been adapted to the U.S. Geological Survey ground-water flow model MODFLOW-2000. The documentation herein is a description of the solver and the adaptation to MODFLOW-2000.

July 13, 2004

SIR 2004-5010. INDIANA.

An Inventory of Aquatic Macroinvertebrates and Calculation of Selected Biotic Indices for the U.S. Army Atterbury Reserve Forces Training Area near Edinburgh, Indiana, September 2000-August 2002. By B.A. Robinson, 19 pages.

Available from USGS Indiana District, 5957 Lakeside Blvd., Indianapolis, IN 46278 (phone 317-290-3333) OR USGS Information Services, Box 25286, Denver Center, Denver, CO 80225 (phone 1-888-ASK-USGS)

Available on-line.

An investigation was conducted to establish an inventory of aquatic macroinvertebrates in the streams at the U.S. Army Atterbury Reserve Forces Training Area near Edinburgh, Indiana. The data used to develop this inventory were collected during two sampling efforts in September 2000 and July and August 2002. The inventory identified 173 distinct taxa within the study-area streams. Although no rare or endangered species were found, one identified species, Cordulegaster maculata Selys (a twin-spotted spiketail dragonfly), is recognized by the Indiana Department of Natural Resources as being rare enough to warrant special concern.

Biotic indices (indicators of water-quality conditions) were calculated from the macroinvertebrate data. Ephemeroptera, Plecoptera, Trichoptera Richness Index values calculated for 23 samples collected from 16 sites ranged from 5 to 15, with more than 75 percent of the values falling within the range of 7 to 11. Hilsenhoff Biotic Index scores and Invertebrate Community Index scores calculated for samples collected at three sites indicate that water quality at these sites ranged from good to poor. The one site with a poor water-quality index score had a small drainage area. The small drainage area and dry conditions during the sampling period may have contributed to the poor scores calculated for this site.

July 9, 2004

other DS89. CALIFORNIA.

Water-Quality Data for Selected Stream Sites in Bridgeport Valley, Mono County, California, April 2000 to June 2003. By Gerald L. Rockwell and Paul D. Honeywell, 35 pages.

Available on line.

The U.S. Geological Survey in cooperation with the California Regional Water Quality Control Board, Lahonton Region, carried out a water-quality data-collection program of selected streams in and near Bridgeport Valley, California, during April 2000 to June 2003. These data were collected to provide information used by the California Regional Water Quality Control Board to develop total maximum daily load standards. Field measurements of streamflow, barometric pressure, dissolved oxygen, pH, specific conductance, and water temperature were made at 15 sites located on 6 streams. Water samples were anlyzed for nutrients, major ions, turbidity, fecal coliform, fecal streptococci, and suspended sediment. Field data, turbidity, nutrient, major ion, and sediment concentrations and fecal coliform and fecal streptocci densities are given in tables for each site. Field blank data are also presented in a table.

July 8, 2004

OFR 2004-1219. CALIFORNIA

Summary of Suspended-Sediment Concentration Data, San Francisco Bay, California, Water Year 2002. By Paul A. Buchanan and Neil K. Ganju, 45 pages.

Available on line.

Suspended-sediment concentration data were collected in San Francisco Bay during water year 2002 (October 1, 2001-September 30, 2002). Optical backscatterance sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, three sites in San Pablo Bay, two sites in Central San Francisco Bay, and three sites in South San Francisco Bay. Sensors were positioned at two depths at most sites. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the electrical output of the optical backscatterance sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes the suspended-sediment concentration data collected from October 2001 through September 2002. Calibration curves and plots of edited data for each sensor also are presented.

July 7, 2004

Available from the U.S. Geological Survey Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4318, 45 p., 2 figs.

A method for the determination of 28 polycyclic aromatic hydrocarbons (PAHs) and 25 alkylated PAH homolog groups in sediment samples is described. The compounds are extracted from sediment by solvent extraction, followed by partial isolation using high-performance gel permeation chromatography. The compounds are identified and quantitated using capillary-column gas chromatography/mass spectrometry. The report presents performance data for full-scan ion monitoring. Method detection limits in laboratory reagent matrix samples range from 1.3 to 5.1 µg/kg for the 28 PAHs. The 25 groups of alkylated PAHs are homologs of five groups of isomeric parent PAHs. Because of the lack of authentic standards, these homologs are reported semiquantitatively using a response factor from a parent PAH or a specific alkylated PAH. Precision data for the alkylated PAH homologs are presented using two different standard reference materials produced by the National Institute of Standards and Technology: SRM 1941b and SRM 1944. The percent relative standard deviations for identified alkylated PAH homolog groups ranged from 1.55 to 6.98 for SRM 1941b and from 6.11 to 12.0 for SRM 1944. Homolog group concentrations reported under this method include the concentrations of individually identified compounds that are members of the group.

Organochlorine (OC) pesticides.including toxaphene, polychlorinated biphenyls (PCBs), and organophosphate (OP) pesticides.can be isolated simultaneously using this method.

In brief, sediment samples are centrifuged to remove excess water and extracted overnight with dichloromethane (95 percent) and methanol (5 percent). The extract is concentrated and then filtered through a 0.2-micrometer polytetrafluoroethylene syringe filter. The PAH fraction is isolated by quantitatively injecting an aliquot of sample onto two polystyrene-divinylbenzene gel-permeation chromatographic columns connected in series. The compounds are eluted with dichloromethane, a PAH fraction is collected, and a portion of the coextracted interferences, including elemental sulfur, is separated and discarded. The extract is solvent exchanged, the volume is reduced, and internal standard is added. Sample analysis is completed using a gas chromatograph/mass spectrometer and full-scan acquisition.

July 1, 2004

SIR 2004-5071. SOUTH DAKOTA.

Streamflow and Water-Quality Characteristics for Wind Cave National Park, South Dakota, 2002-03. By Allen J. Heakin, 68 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5071, 68 p. 7 figs.

Available on line.

A 2-year study of streamflow and water-quality characteristics in Wind Cave National Park was performed by the U.S. Geological Survey in cooperation with the National Park Service. During this study, streamflow and water-quality data were collected for three of the park's perennial streams (Cold Spring, Beaver, and Highland Creeks) from January 2002 through November 2003. The potential influence of parking lot runoff on cave drip within Wind Cave also was investigated by collecting and analyzing several time-dependent samples from a drainage culvert downstream from the parking lot and from Upper Minnehaha Falls inside the cave following a series of simulated runoff events. The primary focus of the report is on data collected during the 2-year study from January 2002 to November 2003; however, data collected previously also are summarized.

Losing reaches occur on both Beaver and Highland Creeks as these streams flow across outcrops of bedrock aquifers within the park. No streamflow losses occur along Cold Spring Creek because its confluence with Beaver Creek is located upstream from the outcrop of the Madison aquifer, where most streamflow losses occur.

Physical properties, major ions, trace elements, nutrients, bacteria, benthic macroinvertebrates, organic (wastewater) compounds, bottom sediment, and suspended sediment are summarized for samples collected from 2 sites on Cold Spring Creek, 2 sites on Beaver Creek, and 1 site on Highland Creek. None of the constituent concentrations for any of the samples collected during 2002-03 exceeded any of the U.S. Environmental Protection Agency drinking-water standards, with the exception of the Secondary Maximum Contaminant Level for pH, which was exceeded in numerous samples from Beaver Creek and Highland Creek. Additionally, the pH values in several of these same samples also exceeded beneficial-use criteria for coldwater permanent fisheries and coldwater marginal fisheries. Water temperature exceeded the coldwater permanent fisheries criterion in numerous samples from all three streams. Two samples from Highland Creek also exceeded the coldwater marginal fisheries criterion for water temperature.

Mean concentrations of ammonia, orthophosphate, and phosphorous were higher for the upstream site on Beaver Creek than for other water-quality sampling sites. Concentrations of E. coli, fecal coliform, and total coliform bacteria also were higher at the upstream site on Beaver Creek than for any other site.

Samples for the analysis of benthic macroinvertebrates were collected from one site on each of the three streams during July 2002 and May 2003. The benthic macroinvertebrate data showed that Beaver Creek had lower species diversity and a higher percentage of tolerant species than the other two streams during 2002, but just the opposite was found during 2003. However, examination of the complete data set indicates that the quality of water at the upstream site was generally poorer than the quality of water at the downstream site. Furthermore, the quality of water at the upstream site on Beaver Creek is somewhat degraded when compared to the quality of water from Highland and Cold Spring Creeks, indicating that anthropogenic activities outside the park probably are affecting the quality of water in Beaver Creek.

Samples for the analysis of wastewater compounds were collected at least twice from four of the five water-quality sampling sites. Bromoform, phenol, caffeine, and cholesterol were detected in samples from Cold Spring Creek, but only phenol was detected at concentrations greater than the minimum reporting level. Concentrations of several wastewater compounds were estimated in samples collected from sites on Beaver Creek, including phenol, para-cresol, and para-nonylphenol-total. Phenol was detected at both sites on Beaver Creek at concentrations greater than the minimum reporting level. Bromoform; para-cresol; ethanol,2-butoxy-phosphate; and cholesterol were detected at Highland Creek; however, none of these concentrations were greater than the minimum reporting level.

The geochemical composition of bottom sediments was analyzed in one composite sample from each of the three streams. Arsenic concentrations of 9.5 micrograms per gram in the sample from Cold Spring Creek and of 9.4 micrograms per gram in the sample from Beaver Creek exceeded the U.S. Environmental Protection Agency's threshold effects guidelines for sediment, the NOAA effects range low value, and the National Irrigation Water Quality Program level of concern. The bottom-sediment sample from Highland Creek had the lowest percentage of organic, organic plus inorganic, and inorganic carbon of any site sampled during this study.

Samples for the analysis of suspended-sediment concentration were collected from each of the five water-quality sampling sites. Of the five sampling sites, mean concentrations of suspended sediment were highest in samples from the upstream site on Cold Spring Creek.

Analyses of water samples collected from the parking lot at the drainage culvert on September 4, 2002, following a simulated runoff event showed that toluene, benzene, meta- and para-xylene, chloroform, methyl isobutyl ketone, and acetone were present in the runoff. Analysis of a background sample collected from Upper Minnehaha Falls prior to the initiation of the simulated runoff event showed that only very low levels of toluene were present and at concentrations less than the minimum reporting level. Traces of acetone, total benzene, ethyl benzene, meta- and para-xylene, ortho-xylene, and styrene were present in the sequential cave-drip samples collected following the simulated runoff event, but at much lower levels than reported by a previous study.

June 30, 2004

WRI 03-4336. KENTUCKY.

Results of a Two-Dimensional Hydrodynamic and Sediment-Transport Model to Predict the Effects of the Phased Construction and Operation of the Olmsted Locks and Dam on the Ohio River near Olmsted, Illinois. By Chad R. Wagner, 61 pages.

Available on line.

The Olmsted two-dimensional hydrodynamic and sediment-transport model was developed in cooperation with the U.S. Army Corps of Engineers, Louisville District. The model was used to estimate the effects that the phased-construction sequence and operation of the Olmsted Locks and Dam had on sediment-transport patterns in the 11.9-mile study reach (Ohio River miles 962.6 to 974.5), particularly over an area of endangered orange-footed pearly mussel (Plethobasus cooperianus) beds beginning approximately 2 miles downstream of the dam construction. A Resource Management Associates.2 (RMA-2) two-dimensional hydrodynamic model for the reach was calibrated to a middle-flow hydraulic survey (350,000 cubic feet per second) and verified with data collected during low- and high-flow hydraulic surveys (72,500 and 770,000 cubic feet per second, respectively). The calibration and validation process included matching water-surface elevations at the construction site and velocity profiles at 15 cross sections throughout the study reach.

The sediment-transport aspect of the project was simulated with the Waterways Experiment Station.s Sed2D model for a 6-year planned-construction period (construction-phase modeling) and a subsequent 3-year operational period (operational-phase modeling). The sediment-transport results from the construction and operational models both were compared to results of concurrent baseline simulations to determine the changes in erosional and depositional patterns induced by the dam construction and operation throughout the study reach and more importantly over the area of the endangered mussel beds.

Simulation of the phased-in-the-wet Olmsted Locks and Dam construction and subsequent operation period resulted in a maximum additional deposition of approximately 2 feet over a localized region of the mussel beds when compared to the bed change simulated with baseline conditions (river conditions that included only the completed locks section). Most areas on the mussel beds experienced less than 0.5 feet of cumulative bed change between the baseline and construction phases during the nine annual hydrographs. The bed change over the 9 year Olmsted Locks and Dam simulation reveals a continuous downstream progression and deepening of the main channel and deposition along the right bank with limited lateral migration toward the more densely populated mussel-bed areas. The sensitivity of the mussels to sediment deposition is difficult to quantify; therefore, the effect of simulated deposition on the welfare of the mussels is uncertain. The model also will provide the U.S. Army Corps of Engineers a tool to predict the locations of high deposition in navigable sections, which can save engineers time and resources when monitoring the need for dredging operations.

June 29, 2004

SIR 2004-5043. OKLAHOMA.

Hydrology and Ground-Water Quality in the Mine Workings within the Picher Mining District, Northeastern Oklahoma, 2002-03. By Kelli L. DeHay, William J. Andrews, and Michael P. Sughru, 62 pages.

U.S. Geological Survey
Information Services
Box 25286
Denver Federal Center
Denver, CO 80225

Available on-line

The Picher mining district of northeastern Ottawa County, Oklahoma, was a major site of mining for lead and zinc ores in the first half of the 20th century. The primary source of lead and zinc were sulfide minerals disseminated in the cherty limestones and dolomites of the Boone Formation of Mississippian age, which comprises the Boone aquifer. Ground water in the aquifer and seeping to surface water in the district has been contaminated by sulfate, iron, lead, zinc, and several other metals. The U.S. Geological Survey, in cooperation with the Oklahoma Department of Environmental Quality, investigated hydrology and ground-water quality in the mine workings in the mining district, as part of the process to aid water managers and planners in designing remediation measures that may restore the environmental quality of the district to pre-mining conditions.

Most ground-water levels underlying the mining district had similar altitudes, indicating a large degree of hydraulic connection in the mine workings and overlying aquifer materials. Recharge-age dates derived from concentrations of chlorofluorocarbons and other dissolved gases indicated that water in the Boone aquifer may flow slowly from the northeast and southeast portions of the mining district. However, recharge-age dates may have been affected by the types of sites sampled, with more recent recharge-age dates being associated with mineshafts, which are more prone to atmospheric interactions and surface runoff than the sampled airshafts.

Water levels in streams upstream from the confluence of Tar and Lytle Creeks were several feet higher than those in adjacent portions of the Boone aquifer, perhaps due to low-permeability streambed sediments and indicating the streams may be losing water to the aquifer in this area. From just upstream to downstream from the confluence of Tar and Lytle Creeks, surface-water elevations in these streams were less than those in the surrounding Boone aquifer, indicating that seepage from the aquifer to downstream portions of Tar Creek was much more likely.

Water properties and major-ion concentrations indicate that water in the mining area was very hard, with large concentrations of dissolved solids that increased from areas of presumed recharge toward areas with older ground water. Most of the ground-water samples, particularly those from the airshafts, had dissolved-oxygen concentrations less than 1.0 milligram per liter. Small concentrations of dissolved oxygen may have been introduced during the sampling process. The small dissolved-oxygen concentrations were associated with samples containing large iron concentrations that indicates possible anoxic conditions in much of the aquifer.

Ground water in the mining district was dominated by calcium, magnesium, and sulfate. Sodium concentrations tended to increase relative to calcium and magnesium concentrations. Ground-water samples collected in 2002-03 had large concentrations of many trace elements. Larger concentrations of metals and sulfate occurred in ground water with smaller pHs and dissolved-oxygen concentrations. Iron was the metal with the largest concentrations in the ground-water samples, occurring at concentrations up to 115,000 micrograms per liter. Cadmium, lead, manganese, zinc, and the other analyzed metals occurred in smaller concentrations in ground water than iron. However, larger cadmium concentrations appeared to be associated with sites that have small iron concentrations and more oxygenated waters. This is noteworthy because the small sulfate and iron concentrations in these waters could lead to conclusions that the waters are less contaminated than waters with large sulfate and iron concentrations.

Ground-water quality in the mining district was compared with subsets of samples collected in 1983-85 and in 2002. Concentrations of most mine-water indicators such as specific conductance, acidity, magnesium, sulfate, and trace elements concentrations decreased over that period. Calcium concentrations did not significantly change.

Mineral saturation indices indicated that the carbonate minerals aragonite, calcite and dolomite, that compose much of the Boone aquifer, were likely to dissolve at most sites. The sulfate minerals of lead (anglesite), barium (barite), cadmium, zinc (goslarite), calcium (gypsum), and iron (melanterite) were generally undersaturated in the ground-water samples, indicating likelihood for dissolution of those minerals and potential for those elements to dissolve into ground water. The clay mineral kaolinite, which is known to form as a hydrolysis product of feldspars at low temperatures, was oversaturated in most of the samples, indicating that it may precipitate out of local ground waters.

Lack of eh (redox) data makes it difficult to interpret the saturation state of the ferric oxyhydroxide minerals. It is likely that the ferric oxyhydroxide minerals could be dissolving, but precipitation is unlikely due to the lack of dissolved oxygen in the mine workings.

June 28, 2004

SIR 2004-5044. MINNESOTA.

Effects of changes in reservoir operations on water quality and trophic-state indicators in Voyageurs National Park, northern Minnesota, 2001-03. By V.G. Christensen, G.A. Payne, and L.W. Kallemeyn, 42 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5004, 42 p.

Implementation of an order by the International Joint Commission in January 2000 has changed operating procedures for dams that regulate two large reservoirs in Voyageurs National Park in northern Minnesota. These new procedures were expected to restore a more natural water regime and affect water levels, water quality, and trophic status. Results of laboratory analyses and field measurements of chemical and physical properties from May 2001 through September 2003 were compared to similar data collected prior to the change in operating procedures. Rank sum tests showed significant decreases in chlorophyll-a concentrations and trophic state indices for Kabetogama Lake (p=0.021) and Black Bay (p=0.007). There were no significant decreases in total phosphorus concentration, however, perhaps due to internal cycling of phosphorus. No sites had significant trends in seasonal total phosphorus concentrations, with the exception of May samples from Sand Point Lake, which had a significant decreasing trend (tau=-0.056, probability=0.03). May chlorophyll-a concentrations for Kabetogama Lake showed a significant decreasing trend (tau=-0.42, probability=0.05). Based on mean chlorophyll trophic-state indices (2001-03), Sand Point, Namakan, and Rainy Lakes would be classified oligotrophic to mesotrophic, and Kabetogama Lake and Rainy Lake at Black Bay would be classified as mesotrophic. The classification of Sand Point, Namakan, and Rainy Lakes remain the same for data collected prior to the change in operating procedures. In contrast, the trophic classification of Kabetogama Lake and Rainy Lake at Black Bay has changed from eutrophic to mesotrophic.

June 25, 2004

OFR 2004-1197. ARIZONA, NEW MEXICO, TEXAS.

Review of knowledge on the occurrence, chemical composition, and potential use for desalination of saline ground water in Arizona, New Mexico, and Texas with a discussion of potential future study needs. By G.F. Huff, pages.

Available on line only.

Increasing demand on the limited supplies of freshwater in the desert Southwest, as well as other parts of the United States, has increased the level of interest in saline-water resources. Saline ground water has long been recognized as a potentially important contributor to water supply in the Southwest, as demonstrated by the number of hydrologic, geologic, and engineering studies on the distribution of saline water and the feasibility of desalination.

Potential future study needs include investigating and documenting the three-dimensional distribution of salinity and chemical composition of saline-water resources and the hydraulic properties of aquifers containing these saline-water resources, assessing the chemical suitability of saline water for use with existing and anticipated desalination technologies, simulating the effect of withdrawal of saline ground water on water levels and water composition in saline and adjoining or overlying freshwater aquifers, and determining the suitability of target geologic formations for injection of desalination-generated waste.

June 23, 2004

SIR 2004-5068. CALIFORNIA.

Evaluation of Methods Used for Estimating Selected Streamflow Statistics, and Flood Frequency and Magnitude, for Small Basins in North Coastal California. By Michael P. Mann, Julé Rizzardo, and Richard Satkowski, 92 pages.

Available on line.

Accurate streamflow statistics are essential to water resource agencies involved in both science and decision-making. When long-term streamflow data are lacking at a site, estimation techniques are often employed to generate streamflow statistics. However, procedures for accurately estimating streamflow statistics often are lacking. When estimation procedures are developed, they often are not evaluated properly before being applied. Use of unevaluated or underevaluated flow-statistic estimation techniques can result in improper water-resources decision-making. The California State Water Resources Control Board (SWRCB) uses two key techniques, a modified rational equation and drainage basin area-ratio transfer, to estimate streamflow statistics at ungaged locations. These techniques have been implemented to varying degrees, but have not been formally evaluated. For estimating peak flows at the 2-, 5-, 10-, 25-, 50-, and 100-year recurrence intervals, the SWRCB uses the U.S. Geological Survey.s (USGS) regional peak-flow equations. In this study, done cooperatively by the USGS and SWRCB, the SWRCB estimated several flow statistics at 40 USGS streamflow gaging stations in the north coast region of California. The SWRCB estimates were made without reference to USGS flow data. The USGS used the streamflow data provided by the 40 stations to generate flow statistics that could be compared with SWRCB estimates for accuracy. While some SWRCB estimates compared favorably with USGS statistics, results were subject to varying degrees of error over the region. Flow-based estimation techniques generally performed better than rain-based methods, especially for estimation of December 15 to March 31 mean daily flows. The USGS peak-flow equations also performed well, but tended to underestimate peak flows. The USGS equations performed within reported error bounds, but will require updating in the future as peak-flow data sets grow larger. Little correlation was discovered between estimation errors and geographic locati! ons or v arious basin characteristics. However, for 25-percentile year mean-daily-flow estimates for December 15 to March 31, the greatest estimation errors were at east San Francisco Bay area stations with mean annual precipitation less than or equal to 30 inches, and estimated 2-year/24-hour rainfall intensity less than 3 inches.

June 23, 2004

WRI 03-4333. OHIO.

Microbiological Water Quality in Relation to Water-Contact Recreation, Cuyahoga River, Cuyahoga Valley National Park, Ohio, 2000 and 2002. By Rebecca N. Bushon and G.F. Koltun, 30 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4333, 30 p., 7 figs., 11 images.

Available on line.

The microbiological water quality of a 23-mile segment of the Cuyahoga River within the Cuyahoga Valley National Park was examined in this study. This segment of the river receives discharges of contaminated water from stormwater, combined-sewer overflows, and incompletely disinfected wastewater. Frequent exceedances of Ohio microbiological water-quality standards result in a health risk to the public who use the river for water-contact recreation.

Water samples were collected during the recreational season of May through October at four sites on the Cuyahoga River in 2000, at three sites on the river in 2002, and from the effluent of the Akron Water Pollution Control Station (WPCS) both years. The samples were collected over a similar range in streamflow in 2000 and 2002. Samples were analyzed for physical and chemical constituents, as well as the following microbiological indicators and pathogenic organisms: Escherichia coli (E. coli), Salmonella, F-specific and somatic coliphage, enterovirus, infectious enterovirus, hepatitis A virus, Clostridium perfringens (C. perfringens), Cryptosporidium, and Giardia. The relations of the microorganisms to each other and to selected water-quality measures were examined.

All microorganisms analyzed for, except Cryptosporidium, were detected at least once at each sampling site. Concentrations of E. coli exceeded the Ohio primary-contact recreational standard (298 colonies per 100 milliliters) in approximately 87 percent of the river samples and generally were higher in the river samples than in the effluent samples. C. perfringens concentrations were positively and significantly correlated with E. coli concentrations in the river samples and generally were higher in the effluent samples than in the river samples.

Several of the river samples that met the Ohio E. coli secondary-contact recreational standard (576 colonies per 100 milliliters) had detections of enterovirus, infectious enterovirus, hepatitis A virus, and Salmonella, indicating that there are still risks even when the E. coli standard is not exceeded. River samples in which the secondary-contact recreational standard for E. coli was exceeded showed a higher percentage of the co-occurrence of pathogenic organisms than samples that met the standard. This indicates that in this study area, E. coli is a useful indicator of human health risk.

Detections of hepatitis A virus tended to be associated with higher median concentrations of somatic coliphage, F-specific coliphage, and infectious enterovirus. In addition, geometric mean C. perfringens concentrations tended to be higher in samples where hepatitis A virus was present than in samples where hepatitis A virus was absent. Hepatitis A virus was not detected in samples collected upstream from the Akron WPCS; all downstream detections had coincident detections in the Akron WPCS effluent, suggesting that Akron WPCS was a principal source of hepatitis A virus at the downstream sites.

Geometric mean concentrations of E. coli were calculated on the basis of analytical results from at least five samples collected at each river site during May, July, and September of 2000. In each case, the Ohio geometric-mean primary-contact recreational standard of 126 col/100 mL was exceeded.

E. coli concentrations were significantly correlated with streamflow and increased with streamflow at sites upstream and downstream from the Akron WPCS. This indicates that E. coli loads from sources upstream from the Akron WPCS have the potential to appreciably influence the frequency of attainment of recreational water-quality standards at downstream locations.

June 22, 2004

other FS 04-3062. ARIZONA, CALIFORNIA, COLORADO, NEVADA, NEW MEXICO, UTAH, WYOMING.

Climatic fluctuations, drought, and flow in the Colorado River. By Robert H. Webb, Gregory J. McCabe, Richard Hereford, and Christopher Wilkowske, 4 pages.

Not yet available in printed form.

Available on line.

Climatic fluctuations have profound effects on water resources in the western United States. In the arid and semiarid parts of the Southwest, climatic fluctuations affect many hydrologic characteristics of watersheds, including the quantity of base flow, the occurrence of large floods, and the timing of snowmelt runoff. Since the start of a persistent drought in about the year 2000, inflows to Lake Powell on the Colorado River have been below average, leading to drawdown of both Lakes Mead and Powell, the primary flow-regulation structures on the river. The recent drought, referred to here as the early 21st century drought, has its origins in several global-scale atmospheric and oceanic processes that reduce delivery of atmospheric moisture to the Colorado River basin. The purpose of this Fact Sheet is to discuss the causes of drought in the Colorado River basin and the predictability of river flows using global climate indices.

June 16, 2004

SIR 2004-5052. WESTERN MONTANA, NORTHERN IDAHO, EASTERN WASHINGTON.

Ground-water quality of selected basin-fill aquifers of the Northern Rockies Intermontane Basins in Montana, Idaho, and Washington. By Rodney R. Caldwell Craig L. Bowers DeAnn M. Dutton, 50 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5052, 50 p., 16 figs.

This report documents the quality of ground water in selected basin-fill aquifers within the Northern Rockies Intermontane Basins Study Unit in western Montana, northern Idaho, and eastern Washington as part of the National Water-Quality Assessment Program (NAWQA). Ground-water samples were collected during the late spring and summer of 1999 and 2001 from 61 wells completed in the basin-fill aquifers. Water samples were analyzed for major ions, nutrients, trace elements, radon, pesticides, volatile organic compounds, and ground-water age-dating constituents. Physical properties of the water, including water temperature, specific conductance, dissolved oxygen, pH, and alkalinity were determined at all sites.

The ground water sampled generally was of good quality and acceptable for most purposes. Measured concentrations of nearly all constituents analyzed were less than U.S. Environmental Protection Agency (USEPA) drinking-water standards. The effects of human activities on ground-water quality were apparent from nitrate and organic-compound concentrations in samples from some wells; however, most concentrations were low and no concentrations exceeded USEPA drinking-water standards. The results of environmental-tracer analyses used for age dating (tritium and sulfur hexaflouride) indicated relatively young ground water (early 1950s or younger recharge water) for all but 2 of 15 samples.

June 16, 2004

WRI 03-4311. PENNSYLVANIA.

Effects of Abandoned Coal-Mine Drainage on Streamflow and Water Quality in the Shamokin Creek Basin, Northumberland and Columbia Counties, Pennsylvania, 1999-2001. By Charles A. Cravotta, III, and Carl S. Kirby, 53 pages.

Available from the USGS Pa. District office, 215 Limekiln Road, New Cumberland, PA 17070 (phone 717-730-6900) and at the USGS libraries in Reston, Va., Denver, Colo., and Menlo Park, Calif., U.S. Geological Survey Water-Resources Investigations Report 03-4311, 53 p., 13 figs., 3 appendixes [CD-ROM].

Available on line.

This report assesses the contaminant loading, effects to receiving streams, and possible remedial alternatives for abandoned mine drainage (AMD) within the upper Shamokin Creek Basin in east-central Pennsylvania. The upper Shamokin Creek Basin encompasses an area of 54 square miles (140 square kilometers) within the Western Middle Anthracite Field, including and upstream of the city of Shamokin. Elevated concentrations of acidity, metals, and sulfate in the AMD from flooded underground anthracite coal mines and (or) unreclaimed culm (waste rock) piles degrade the aquatic ecosystem and water quality of Shamokin Creek to its mouth and along many of its tributaries within the upper basin. Despite dilution by unpolluted streams that more than doubles the streamflow of Shamokin Creek in the lower basin, AMD contamination and ecological impairment persist to its mouth on the Susquehanna River at Sunbury, 20 miles (32 kilometers) downstream from the mined area.

Aquatic ecological surveys were conducted by the U.S. Geological Survey (USGS) in cooperation with Bucknell University (BU) and the Northumberland County Conservation District (NCCD) at six stream sites in October 1999 and repeated in 2000 and 2001 on Shamokin Creek below Shamokin and at Sunbury. In 1999, fish were absent from Quaker Run and Shamokin Creek upstream of its confluence with Carbon Run; however, creek chub (Semotilus atromaculatus) were present within three sampled reaches of Carbon Run. During 1999, 2000, and 2001, six or more species of fish were identified in Shamokin Creek below Shamokin and at Sunbury despite elevated concentrations of dissolved iron and iron-encrusted streambeds at these sites.

Data on the flow rate and chemistry for 46 AMD sources and 22 stream sites throughout the upper basin plus 1 stream site at Sunbury were collected by the USGS with assistance from BU and the Shamokin Creek Restoration Alliance (SCRA) during low base-flow conditions in August 1999 and high base-flow conditions in March 2000. The water-quality data were used to determine priority ranks of the AMD sources on the basis of loadings of iron, manganese, and aluminum and to identify possible remedial alternatives, including passive-treatment options, for consideration by water-resource managers. The ranking sequence for the top AMD sources based on the high base-flow data generally matched that based on the low base-flow data. The contaminant loadings generally increased with flow, and 10 previously identified intermittent AMD sources were not discharging during the low base-flow sampling period. The top 3 AMD sources (SR19, SR12, and SR49) on the basis of dissolved metals loading in March 2000 accounted for more than 50 percent of the metals loading to Shamokin Creek, whereas the top 15 AMD sources accounted for more than 98 percent of the metals loading. When sampled in March 2000, these AMD sources had flow rates ranging from 0.7 to 19 cubic feet per second (1,138 to 32,285 liters per minute) and pH from 3.5 to 6.1 standard units. Only 1 of the top 15 AMD sources (SR21) was net alkaline (alkalinity > acidity); the others were net acidic and will require additional alkalinity to facilitate metals removal and maintain near-neutral pH. For the top 15 AMD sources, dissolved iron was the principal source of acidity and metals loading; concentrations of iron ranged from 10 to 57 milligrams per liter. Dissolved manganese ranged from 1.9 to 7.4 milligrams per liter. Dissolved aluminum exceeded 3.9 milligrams per liter at seven of the sites but was less than 0.2 milligram per liter at seven others.

Alkalinity can be acquired by the dissolution of limestone and (or) bacterial sulfate reduction within various passive-treatment systems including anoxic or oxic limestone drains, limestone- lined channels, or compost wetlands. Subsequently, the gradual oxidation and consequent precipitation of iron and manganese can be accommodated within settling ponds or aerobic wetlands. Assuming an iron removal rate of 180 pounds per acre per day (20 grams per square meter per day), constructed treatment wetlands at the top 15 AMD sites would require a minimum area ranging from 0.7 to 17.8 acres (590 to 71,670 square meters). Implementation of passive treatment would not be feasible at most of the top 15 and many lower priority AMD sites considering the proximity of many discharges to streams, roads, or railroads, and the limited availability or access to land at the discharge location. The reduction of infiltration and removal of culm waste and (or) the relocation of the discharge to nearby areas could decrease the AMD quantities and facilitate treatment at some of the priority AMD sites.

June 2, 2004

WRI 03-4186. NEW MEXICO.

Questa baseline and pre-mining ground-water quality investigation. 3. Historical ground-water quality for the Red River Valley, New Mexico. By S.H. LoVetere, D.K. Nordstrom, A.S. Maest, and C.A. Naus, 49 pages.

Available from USGS Information Services, Box 25286, Denver Federal Center, Denver, Colorado, 80225-0286, USGS Water-Resources Investigations Report 03-4186, 49 p., 18 figs., plus CD.

Historical ground-water quality data for 100 wells in the Red River Valley between the U.S. Geological Survey streamflow-gaging station (08265000), near Questa, and Placer Creek east of the town of Red River, New Mexico, were compiled and reviewed. The tabulation included 608 water-quality records from 23 sources entered into an electronic database. Ground-water quality data were first collected at the Red River wastewater-treatment facility in 1982. Most analyses, however, were obtained between 1994 and 2002, even though the first wells were developed in 1962.

The data were evaluated by considering (a) temporal consistency, (b) quality of sampling methods, (c) charge imbalance, and (d) replicate analyses. Analyses that qualified on the basis of these criteria were modeled to obtain saturation indices for gypsum, calcite, fluorite, gibbsite, manganite, and rhodocrosite. Plots created from the data illustrate that water chemistry in the Red River Valley is predominantly controlled by calcite dissolution, congruent gypsum dissolution, and pyrite oxidation.

May 26, 2004

other Fact Sheet 2004-3026. COLORADO, KANSAS, NEBRASKA, NEW MEXICO, OKLAHOMA, SOUTH DAKOTA, TEXAS, and WYOMING.

Water-level changes in the High Plains aquifer, predevelopment to 2002, 1980 to 2002, and 2001 to 2002. By Virginia L. McGuire, 6 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Fact Sheet 2004-3026, 6 p., 4 figs.

Available on line.

A new report by the U.S. Geological Survey (USGS) describes changes that have taken place in the High Plains aquifer from the time that substantial ground-water pumping began, which was generally in the 1940's and is termed "predevelopment," to the year 2002. According to the new report, "Water-level changes in the High Plains aquifer, predevelopment to 2002, 1980 to 2002, and 2001 to 2002" by V.L. McGuire, water in storage in the High Plains (or Ogallala) aquifer declined about 200 million acre-feet from predevelopment to 2002, 67 million acre-feet from 1980 to 2002 and 10 million acre-feet from 2001 to 2002.

Underlying parts of eight states, including Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, and Texas, the High Plains aquifer spans 173,000 square miles, provides irrigation for one of the major agricultural regions in the world, and supplies drinking water for 82 percent of the people who live within the aquifer boundaries. Water levels in the High Plains aquifer started to decline soon after the beginning of extensive ground-water irrigation development. USGS scientists mapped water-level changes using data collected by the USGS, other Federal, State, and local agencies between the years 1920 and 2002 from more than 20,000 wells screened in the High Plains aquifer. A network of about 9,200 wells was used to monitor water levels in the aquifer in 2002. The predevelopment water level generally was estimated by using the earliest water-level measurement available. USGS scientists calculated change in water in storage using the maps of water-level changes for each comparison period and the average specific yield of the aquifer in each State.

May 4, 2004

WRI 03-4047.

Development and Application of Watershed Regressions for Pesticides (WARP) for Estimating Atrazine Concentration Distributions in Streams. By Steven J. Larson, Charles G. Crawford, and Robert J. Gilliom, 68 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4047, 68 p., 44 figs.

Available on line.

Regression models were developed for predicting atrazine concentration distributions in rivers and streams, using the Watershed Regressions for Pesticides (WARP) methodology. Separate regression equations were derived for each of nine percentiles of the annual distribution of atrazine concentrations and for the annual time-weighted mean atrazine concentration. In addition, seasonal models were developed for two specific periods of the year.the high season, when the highest atrazine concentrations are expected in streams, and the low season, when concentrations are expected to be low or undetectable. Various nationally available watershed parameters were used as explanatory variables, including atrazine use intensity, soil characteristics, hydrologic parameters, climate and weather variables, land use, and agricultural management practices. Concentration data from 112 river and stream stations sampled as part of the U.S. Geological Survey.s National Water-Quality Assessment and National Stream Quality Accounting Network Programs were used for computing the concentration percentiles and mean concentrations used as the response variables in regression models. Tobit regression methods, using maximum likelihood estimation, were used for developing the models because some of the concentration values used for the response variables were censored (reported as less than a detection threshold). Data from 26 stations not used for model development were used for model validation. The annual models accounted for 62 to 77 percent of the variability in concentrations among the 112 model development stations. Atrazine use intensity (the amount of atrazine used in the watershed divided by watershed area) was the most important explanatory variable in all models, but additional watershed parameters significantly increased the amount of variability explained by the models. Predicted concentrations from all 10 models were within a factor of 10 of the observed concentrations at most model development and model validation stations. Results for the two sets of seasonal models were similar. Concentration distributions derived from the seasonal-model predictions provided additional information compared to distributions derived from the annual models.

May 4, 2004

CIR 1254.

The World's Largest Floods, Past and Present: Their Causes and Magnitudes. By Jim E. O'Connor and John E. Costa, 13 pages.

Available on line.

Floods are among the most powerful forces on earth. Human societies worldwide have lived and died with floods from the very beginning, spawning a prominent role for floods within legends, religions, and history. Inspired by such accounts, geologists, hydrologists, and historians have studied the role of floods on humanity and its supporting ecosystems, resulting in new appreciation for the many-faceted role of floods in shaping our world. Part of this appreciation stems from ongoing analysis of long-term streamflow measurements, such as those recorded by the U.S. Geological Survey's (USGS) streamflow gaging network. But the recognition of the important role of flooding in shaping our cultural and physical landscape also owes to increased understanding of the variety of mechanisms that cause floods and how the types and magnitudes of floods can vary with time and space. The USGS has contributed to this understanding through more than a century of diverse research activities on many aspects of floods, including their causes, effects, and hazards. This Circular summarizes a facet of this research by describing the causes and magnitudes of the world's largest floods, including those measured and described by modern methods in historic times, as well as floods of prehistoric times, for which the only records are those left by the floods themselves.

May 4, 2004

FS 2004-3012. CALIFORNIA.

Water-Quality Assessment of the San Joaquin-Tulare Basins--Entering a New Decade. By Jo Ann M. Gronberg, Charles R. Kratzer, Karen R. Burow, Joseph L. Domagalski, and Stephen P. Phillips, 6 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Fact Sheet 2004-3012, 6 p., 5 figs.

Available on line.

In 1991, the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey began to address the need for consistent and scientifically sound information for managing the Nation's water resources. The long-term goals of this program are to assess the status of the quality of freshwater streams and aquifers, to describe trends or changes in water quality over time, and to provide a sound understanding of the natural and human factors that affect the quality of these resources (Hirsch and others, 1988). Investigations are being conducted within major river basins and aquifer systems, or "study units," throughout the Nation to provide a framework for national and regional water-quality assessments.

In 2001, the NAWQA Program begain its second decade of intensive water-quality assessments. Forty-two of the original 59 study units (reduced by elimination or combination) are being revisited (Gilliom and others, 2001). The San Joaquin-Tulare Basins study unit located in Central California, was part of the first decadal cycle of the Program investigations and remains in the second cycle.

May 3, 2004

WRI 03-4132. ARKANSAS, LOUISIANA.

Development and calibration of a ground-water flow model for the Sparta aquifer of southeastern Arkansas and north-central Louisiana and simulated response to withdrawals, 1998-2027. By Paul W. McKee and Brian R. Clark, 71 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4132, 71 p., 33 figs., and 9 tables.

Available on line.

The Sparta aquifer, which consists of the Sparta Sand, in southeastern Arkansas and north-central Louisiana is a major water resource and provides water for municipal, industrial, and agricultural uses. In recent years, the demand in some areas has resulted in withdrawals from the Sparta aquifer that substantially exceed replenishment of the aquifer. Considerable drawdown has occurred in the potentiometric surface forming regional cones of depression as water is removed from storage by withdrawals. These cones of depression are centered beneath the Grand Prairie area and the cities of Pine Bluff and El Dorado in Arkansas, and Monroe in Louisiana. The rate of decline for hydraulic heads in the aquifer has been greater than 1 foot per year for more than a decade in much of southern Arkansas and northern Louisiana where hydraulic heads are now below the top of the Sparta Sand. Continued hydraulic-head declines have caused water users and managers alike to question the ability of the aquifer to supply water for the long term. Concern over protecting the Sparta aquifer as a sustainable resource has resulted in a continued, cooperative effort by the Arkansas Soil and Water Conservation Commission, U.S. Army Corps of Engineers, and the U.S. Geological Survey to develop, maintain, and utilize numerical ground-water flow models to manage and further analyze the ground-water system. The work presented in this report describes the development and calibration of a ground-water flow model representing the Sparta aquifer to simulate observed hydraulic heads, documents major differences in the current Sparta model compared to the previous Sparta model calibrated in the mid-1980.s, and presents the results of three hypothetical future withdrawal scenarios.

The current Sparta model.a regional scale, three-dimensional numerical ground-water flow model.was constructed and calibrated using available hydrogeologic, hydraulic, and water-use data from 1898 to 1997. Significant changes from the previous model include grid rediscretization of the aquifer, extension of the active model area northward beyond the Cane River Formation facies change, and representation of model boundaries. The current model was calibrated with the aid of parameter estimation, a nonlinear regression technique, combined with trial and error parameter adjustment using a total of 795 observations from 316 wells over 4 different years.1970, 1985, 1990, and 1997. The calibration data set provides broad spatial and temporal coverage of aquifer conditions. Analysis of the residual statistics, spatial distribution of residuals, simulated compared to observed hydrographs, and simulated compared to observed potentiometric surfaces were used to analyze the ability of the calibrated model to simulate aquifer conditions within acceptable error. The calibrated model has a root mean square error of 18 feet for all observations, an improvement of more than 12 feet from the previous model.

The current Sparta model was used to predict the effects of three hypothetical withdrawal scenarios on hydraulic heads over the period 1998-2027 with one of those extended indefinitely until equilibrium conditions were attained, or steady state. In scenario 1a, withdrawals representing the time period from 1990 to 1997 was held constant for 30 years from 1998 to 2027. Hydraulic heads in the middle of the cone of depression centered on El Dorado decreased by 10 feet from the 1997 simulation to 222 feet below NGVD of 1929 in 2027. Hydraulic heads in the Pine Bluff cone of depression showed a greater decline from 61 feet below NGVD of 1929 to 78 feet below NGVD of 1929 in the center of the cone. With these same withdrawals extended to steady state (scenario 1b), hydraulic heads in the Pine Bluff cone of depression center declined an additional 26 feet to 104 feet below NGVD of 1929, while the hydraulic-head decline in the El Dorado cone of depression center was only an additional 7 feet.

In scenario 2, withdrawals were extended as in scenario 1a while reducing withdrawals in industrial areas in Pine Bluff and El Dorado, Arkansas. Selected pumpage was removed to simulate effects of industry changing to alternate sources of water. Removal of selected withdrawal points in both the Pine Bluff and El Dorado areas results in shallower, less expansive cones of depression compared to scenario 1a. In the cone of depression centers, hydraulic heads recovered more than 120 and 165 feet, respectively, in the Pine Bluff and El Dorado areas. With this recovery, the area of Union County where hydraulic heads are below the top of the Sparta Sand decreased from 51.9 percent in 1997 to 7.3 percent by 2027.

In scenario 3, withdrawals gradually were increased 25 percent over 30 years while withdrawals were reduced in industrial areas of Jefferson and Union Counties. The results are similar to scenario 2, however, magnitudes of recovery are less because of continued increases in withdrawals elsewhere in the aquifer. In the cone of depression centers for Pine Bluff and El Dorado, hydraulic heads recovered more than 100 and 124 feet, respectively. Even though substantial hydraulic-head recovery occurred in both scenarios 2 and 3, hydraulic heads continued to decline in the Grand Prairie area and in much of north-central Louisiana as withdrawals increased through 2027.

May 3, 2004

WRI 03-4231. ARKANSAS, LOUISIANA.

Conjunctive-use optimization model and sustainable-yield estimation for the Sparta aquifer of southeastern Arkansas and north-central Louisiana. By Paul W. McKee, Brian R. Clark, and John B. Czarnecki, 30 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, Colorado 80225, USGS Water-Resources Investigations Report 03-4231, 30 p., 8 figs, and 4 tables.

Available on line.

Conjunctive-use optimization modeling was done to assist water managers and planners by estimating the maximum amount of ground water that hypothetically could be withdrawn from wells within the Sparta aquifer indefinitely without violating hydraulic-head or stream-discharge constraints. The Sparta aquifer is largely a confined aquifer of regional importance that comprises a sequence of unconsolidated sand units that are contained within the Sparta Sand. In 2000, more than 35.4 million cubic feet per day (Mft3/d) of water were withdrawn from the aquifer by more than 900 wells, primarily for industry, municipal supply, and crop irrigation in Arkansas. Continued, heavy withdrawals from the aquifer have caused several large cones of depression, lowering hydraulic heads below the top of the Sparta Sand in parts of Union and Columbia Counties and several areas in north-central Louisiana. Problems related to overdraft in the Sparta aquifer can result in increased drilling and pumping costs, reduced well yields, and degraded water quality in areas of large drawdown.

A finite-difference ground-water flow model was developed for the Sparta aquifer using MODFLOW, primarily in eastern and southeastern Arkansas and north-central Louisiana. Observed aquifer conditions in 1997 supported by numerical simulations of ground-water flow show that continued pumping at withdrawal rates representative of 1990 - 1997 rates cannot be sustained indefinitely without causing hydraulic heads to drop substantially below the top of the Sparta Sand in southern Arkansas and north-central Louisiana. Areas of ground-water levels below the top of the Sparta Sand have been designated as Critical Ground-Water Areas by the State of Arkansas. A steady-state conjunctive-use optimization model was developed to simulate optimized surface-water and ground-water withdrawals while maintaining hydraulic-head and streamflow constraints, thus determining the "sustainable yield" for the aquifer.

Initial attempts to estimate sustainable yield using simulated 1997 hydraulic heads as initial heads in Scenario 1 and 100 percent of the baseline 1990-1997 withdrawal rate as the lower specified limit in Scenario 2 led to infeasible results. Sustainable yield was estimated successfully for scenario 3 with three variations on the upper limit of withdrawal rates. Additionally, ground-water withdrawals in Union County were fixed at 35.6 percent of the baseline 1990-1997 withdrawal rate in Scenario 3. These fixed withdrawals are recognized by the Arkansas Soil and Water Conservation Commission to be sustainable as determined in a previous study. The optimized solutions maintained hydraulic heads at or above the top of the Sparta Sand (except in the outcrop areas where unconfined conditions occur) and streamflow within the outcrop areas was maintained at or above minimum levels. Scenario 3 used limits of 100, 150, and 200 percent of baseline 1990-1997 withdrawal rates for the upper specified limit on 1,119 withdrawal decision variables (managed wells) resulting in estimated sustainable yields ranging from 11.6 to 13.2 Mft3/d in Arkansas and 0.3 to 0.5 Mft3/d in Louisiana. Assuming the total water demand is equal to the baseline 1990-1997 withdrawal rates, the sustainable yields estimated from the three scenarios only provide 52 to 59 percent of the total ground-water demand for Arkansas; the remainder is defined as unmet demand that could be obtained from large, sustainable surface-water withdrawals.

May 3, 2004

WRI 03-4319. MONTANA.

Wildfire-related floods and debris flows in Montana in 2000 and 2001. By Charles Parrett Susan H. Cannon Kenneth L. Pierce, 22 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4319, 22 p., 9 fig.

Following extensive wildfires in summer 2000, Montana experienced flooding and debris flows in three different burned areas: the Bitterroot area in southwestern Montana, the Canyon Ferry area near Helena, and the Ashland area in southeastern Montana.

Flooding and debris flow in the Bitterroot study area began with a large, frontal storm in September-October 2000. The storm resulted in debris flows and a peak flood discharge on Little Sleeping Child Creek that had a recurrence interval of about 100 years.

Beginning in May 2001, some streams in the Canyon Ferry area flooded in response to thunderstorms. Recurrence intervals for the calculated peak discharges on four small drainages, based on unburned conditions, ranged from 2 years to 200 years.

Tributaries to Otter Creek and the Tongue River flooded in response to June and July 2001 thunderstorms in the Ashland area. Recurrence intervals for calculated peak stream discharges, based on unburned conditions, ranged from 50 to 500 years.

In July 2001, thunderstorms in the Bitterroot area caused flooding on several small streams and significant debris-flow activity on tributaries to Sleeping Child Creek. The maximum recurrence interval for peak discharges, based on unburned conditions, was 200-500 years for two sites on Laird Creek.

April 29, 2004

WDR ND-03-1. NORTH DAKOTA.

Water Resources Data, North Dakota Water Year 2003, Volume 1. Surface Water. By S.M. Robinson, R.F. Lundgren, B.A. Sether, S.W. Norbeck, and J.M. Lambrecht, 583 pages.

National Technical Information Service Springfield, VA 22161

Available on line.

Water-resources data for the 2003 water year for North Dakota consists of records of discharge, stage, and water quality for streams; contents, stage, and water quality for lakes and reservoirs; and water levels and water quality for ground-water wells. Volume 1 contains records of water discharge for 108 streamflow-gaging stations; stage only for 24 river-stage stations; contents and/or stage for 14 lake or reservoir stations; annual maximum discharge for 32 crest-stage stations; and water-quality for 99 streamflow-gaging stations, 5 river-stage stations, 11 lake or reservoir stations, 8 miscellaneous sample sites on rivers, and 63 miscellaneous sample sites on lakes and wetlands. Data are included for 7 water-quality monitor sites on streams and 2 precipitation-chemistry stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating Federal, State, and local agencies in North Dakota.

April 29, 2004

WRI 03-4291. NORTH DAKOTA, MINNESOTA, SOUTH DAKOTA.

Regression Equations for Estimating Concentrations of Selected Water-Quality Constituents for Selected Gaging Stations in the Red River of the North Basin, North Dakota, Minnesota, and South Dakota. By Tara Williams-Sether, 33 pages.

Available on line.

The Dakota Water Resources Act, passed by the U.S. Congress on December 15, 2000, authorized the Secretary of the Interior to conduct a comprehensive study of future water-quantity and quality needs of the Red River of the North Basin in North Dakota and possible options to meet those water needs. Previous Red River of the North Basin studies conducted by the Bureau of Reclamation used streamflow and water-quality data bases developed by the U.S. Geological Survey that included data for 1931-84. As a result of the recent congressional authorization and results of previous studies by the Bureau of Reclamation, redevelopment of the streamflow and water-quality data bases with current data through 1999 are needed in order to evaluate and predict the water-quantity and quality effects within the Red River of the North Basin. This report provides updated statistical summaries of selected water-quality constituents and streamflow and the regression relations between them.

Available data for 1931-99 were used to develop regression equations between 5 selected water-quality constituents and streamflow for 38 gaging stations in the Red River of the North Basin. The water-quality constituents that were regressed against streamflow were hardness (as CaCO3), sodium, chloride, sulfate, and dissolved solids. Statistical summaries of the selected water-quality constituents and streamflow for the gaging stations used in the regression equations development and the applications and limitations of the regression equations are presented in this report.

April 29, 2004

Estimated Use of Water in the Tennessee River Watershed in 2000 and Projections of Water Use to 2030. By Susan S. Hutson, M. Carolyn Koroa, and C. Michael Murphree, 89 pages.

Available from the U.S. Geological Survey Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4302, 89 p., 28 figs.

Estimates indicate that after increases in water withdrawals from 1965 to 1980 in the Tennessee River watershed, withdrawals declined from 1980 to 1985 and remained steady from 1985 to 1995. Water withdrawals in the Tennessee River watershed during 2000 averaged about 12,211 million gallons per day (Mgal/d) of freshwater for offstream uses.22 percent more than the 1995 estimate. The 2000 estimate is nearly the same as the estimate for 1980, the highest year of record, with 12,260 Mgal/d. The reuse potential of water from the Tennessee River is high because most of the water withdrawn for offstream use is returned to the river system. Besides water quality, reuse potential reflects the quantity of water available for subsequent uses and is gaged by consumptive use, which is the difference between water withdrawals and return flow. For the Tennessee River watershed, return flow was estimated to be 11,562 Mgal/d, or 95 percent of the water withdrawn during 2000. Total consumptive use accounts for the remaining 5 percent, or 649 Mgal/d.

Estimates of water withdrawals by source indicate that during 2000, withdrawals from surface water accounted for 98 percent of the total withdrawals, or 11,996 Mgal/d, 23 percent more than during 1995. Total ground-water withdrawals during 2000 were 215 Mgal/d, or 17 percent less than during 1995.

During 2000, thermoelectric power withdrawals were estimated to be 10,276 Mgal/d; industrial, 1,205 Mgal/d; public supply, 662 Mgal/d; and irrigation, 68.9 Mgal/d. Return flows were estimated to be: thermoelectric power, 10,244 Mgal/d; industrial, 942 Mgal/d; and public supply, 377 Mgal/d. Consumptive use was estimated to be: thermoelectric power, 32.2 Mgal/d; industrial, 263 Mgal/d; public supply, 285 Mgal/d; and irrigation, 68.9 Mgal/d. Each category of use affects the reuse potential of the return flows differently. The consumptive use in the river is comparatively small because most of the water withdrawn from the Tennessee River watershed is used for once-through cooling for the thermoelectric power and industrial sectors.

Average per capita use for all offstream uses was 2,710 gallons per day per person in 2000, compared to the record high of 3,200 in 1975 and 1980. The intensity of use for the Tennessee River watershed as measured as a function of area was 298,489 gallons per day per square mile in 2000.

In 2030, water withdrawals are projected to increase by about 15 percent to 13,990 Mgal/d. By category, water withdrawals are projected to increase as follows: thermoelectric power, 11 percent or 1,152 Mgal/d; industry, 31 percent or 368 Mgal/d; public supply, 35 percent or 232 Mgal/d; and irrigation, 37 percent or 25.2 Mgal/d. Total consumptive use is projected to increase about 51 percent or 334 Mgal/d to 980 Mgal/d. Per capita use in 2030 is calculated to be about 2,370 gallons per day, about 26 percent less than in 1980. Water transfers to the Tennessee-Tombigbee waterway for navigation lockages were estimated as 200 Mgal/d for 2000 and 800 Mgal/d for 2030. Water transfers for hydropower commitments through Barkley Canal averaged 3,361 Mgal/d for 2000 and are estimated to be an average of 4,524 Mgal/d in 2030.

April 20, 2004

WRI 03-4293.

Methods of Analysis by the U.S. Geological Survey National Water Quality Laboratory--Determination of Organochlorine Pesticides and Polychlorinated Biphenyls in Bottom and Suspended Sediment by Gas Chromatography with Electron-Capture Detection. By Mary C. Noriega, Duane S. Wydoski, and William T. Foreman, 46 pages.

Available from the U.S. Geological Survey Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4293, 46 p., 8 figs.

A method applicable for the determination of 19 organochlorine (OC) pesticides, including total toxaphene as a complex mixture, and 3 polychlorinated biphenyl (PCB) mixtures as Aroclor® equivalents—Aroclor 1016/1242, 1254, and 1260—in soil, aquatic bottom sediment, and suspended sediment is described. Method performance data are presented. The solvent system is designed to extract simultaneously selected OC pesticides and PCBs from the same sample matrix. The compounds are extracted by conventional Soxhlet extraction with dichloromethane, followed by partial isolation using gel permeation chromatography (GPC) to remove inorganic sulfur and large naturally present molecules from the sediment extract. The aliquot of extract collected from the GPC for OCs (OC pesticides and PCBs) is split into two sample fractions by alumina/silica combined-column chromatography, followed by Florisil adsorption chromatography to remove interfering compounds in the second fraction. The OC fractions are analyzed by dual capillary-column gas chromatography with electron-capture detection (GC/ECD). This report is limited to the determination of selected OC pesticides and PCBs by GC/ECD using this method. Interim reporting levels (IRLs) have been set at 0.400 to 3.12 micrograms per kilogram (µg/kg) for 18 individual OC pesticides, 200 µg/kg for toxaphene, and 4.04 to 4.68 µg/kg for the PCBs, based on a sample size of 25-gram equivalent dry weight. These reporting levels may change following additional determinations of method detection limits.

April 20, 2004

OFR 2004-1076. NORTH DAKOTA and MINNESOTA.

River Gain and Loss Studies for the Red River of the North Basin, North Dakota and Minnesota. By Tara Williams-Sether, 21 pages.

Available on line.

The Dakota Water Resources Act passed by the U.S. Congress in 2000 authorized the Secretary of the Interior to conduct a comprehensive study of future water-quantity and -quality needs of the Red River of the North (Red River) Basin in North Dakota and of possible options to meet those water needs. To obtain the river gain and loss information needed to properly account for available streamflow within the basin, available river gain and loss studies for the Sheyenne, Turtle, Forest, and Park Rivers in North Dakota and the Wild Rice, Sand Hill, Clearwater, South Branch Buffalo, and Otter Tail Rivers in Minnesota were reviewed. Ground-water discharges for the Sheyenne River in a reach between Lisbon and Kindred, N. Dak., were about 28.8 cubic feet per second in 1963 and about 45.0 cubic feet per second in 1986. Estimated monthly net evaporation losses for additional flows to the Sheyenne River from the Missouri River ranged from 1.4 cubic feet per second in 1963 to 51.0 cubic feet per second in 1976. Maximum water losses for a reach between Harvey and West Fargo, N. Dak., for 1956-96 ranged from about 161 cubic feet per second for 1976 to about 248 cubic feet per second for 1977. Streamflow gains of 1 to 1.5 cubic feet per second per mile were estimated for the Wild Rice, Sand Hill, and Clearwater Rivers in Minnesota. The average ground-water discharge for a 5.2-mile reach of the Otter Tail River in Minnesota was about 14.1 cubic feet per second in August 1994. The same reach lost about 14.1 cubic feet per second between February 1994 and June 1994 and about 21.2 cubic feet per second between August 1994 and August 1995.

April 15, 2004

WRI WRIR 03-4300. CONNECTICUT.

Water Use, Ground-Water Recharge and Availability, and Quality of Water in the Greenwich Area, Fairfield County, Connecticut and Westchester County, New York, 2000-2002. By John R. Mullaney, 64 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225

Ground-water budgets were developed for 32 small basin-based zones in the Greenwich area of southwestern Connecticut, where crystalline-bedrock aquifers supply private wells, to determine the status of residential ground-water consumption relative to rates of ground-water recharge and discharge. Estimated residential ground-water withdrawals for small basins (averaging 1.7 square miles (mi2)) ranged from 0 to 0.16 million gallons per day per square mile (Mgal/d/mi2). To develop these budgets, residential ground-water withdrawals were estimated using multiple-linear regression models that relate water use from public water supply to data on residential property characteristics. Average daily water use of households with public water supply ranged from 219 to 1,082 gallons per day (gal/d).

A steady-state finite-difference ground-water-flow model was developed to track water budgets, and to estimate optimal values for hydraulic conductivity of the bedrock (0.05 feet per day) and recharge to the overlying till deposits (6.9 inches) using nonlinear regression. Estimated recharge rates to the small basins ranged from 3.6 to 7.5 inches per year (in/yr) and relate to the percentage of the basin underlain by coarse-grained glacial stratified deposits. Recharge was not applied to impervious areas to account for the effects of urbanization. Net residential ground-water consumption was estimated as ground-water withdrawals increased during the growing season, and ranged from 0 to 0.9 in/yr.

Long-term average stream base flows simulated by the ground-water-flow model were compared to calculated values of average base flow and low flow to determine if base flow was substantially reduced in any of the basins studied. Three of the 32 basins studied had simulated base flows less than 3 in/yr, as a result of either ground-water withdrawals or reduced recharge due to urbanization. A water-availability criteria of the difference between the 30-day 2-year low flow and the recharge rate for each basin was explored as a method to rate the status of water consumption in each basin. Water consumption ranged from 0 to 14.3 percent of available water based on this criteria for the 32 basins studied.

Base-flow water quality was related to the amount of urbanized area in each basin sampled. Concentrations of total nitrogen and phosphorus, chloride, indicator bacteria, and the number of pesticide detections increased with basin urbanization, which ranged from 18 to 63 percent of basin area.

April 13, 2004

WRI 03-4232. ARKANSAS, LOUISIANA.

Recalibration of a ground-water flow model of the Mississippi River Valley alluvial aquifer in southeastern Arkansas, 1918-1998, with simulations of hydraulic heads caused by projected ground-water withdrawals through 2049. By Gregory P. Stanton and Brian R. Clark, 48 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4232, 48 p., 27 figs., and 5 tables.

Available on line.

The Mississippi River Valley alluvial aquifer, encompassing parts of Arkansas, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee supplies an average of 5 billion gallons of water per day. However, withdrawals from the aquifer in recent years have caused considerable drawdown in the hydraulic heads in southeastern Arkansas and other areas. The effects of current ground-water withdrawals and potential future withdrawals on water availability are major concerns of water managers and users as well as the general public. A full understanding of the behavior of the aquifer under various water-use scenarios is critical for the development of viable water-management and alternative source plans. To address these concerns, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, Vicksburg District, and the Arkansas Soil and Water Conservation Commission developed and calibrated a ground-water flow model for the Mississippi River valley alluvial aquifer in southeastern Arkansas to simulate hydraulic heads caused by projected ground-water withdrawals.

A previously published ground-water flow model for the alluvial aquifer in southeastern Arkansas was updated and recalibrated to reflect more current pumping stresses with additional stress periods added to bring the model forward from 1982 to 1998. The updated model was developed and calibrated with MODFLOW-2000 finite difference numerical modeling and parameter estimation software. The model was calibrated using hydraulic-head data collected during 1972 and 1982 and hydraulic-head measurements made during spring (February to April) of 1992 and 1998. The residuals for 1992 and 1998 have a mean absolute value of 4.74 and 5.45 feet, respectively, and a root mean square error of 5.9 and 6.72 feet, respectively.

The effects of projected ground-water withdrawals were simulated through 2049 in three predictive scenarios by adding five additional stress periods of 10 years each. In the three scenarios, pumpage was defined by either continuing 1997 pumpage into the future (scenario 1) or by continuing water-use trends into the future (scenario 2), and increasing water-use trends with a 10 percent reduction in pumpage in selected areas (scenario 3). Scenario 1 indicates a cone of depression centered in Desha County and extensive dewatering with areas of simulated hydraulic heads dropping below 50 percent saturated thickness. Scenario 2 indicates a larger area of simulated hydraulic heads dropping below 50 percent saturated thickness and additional dewatering with model cells going dry and smaller cones of depression appearing in Ashley and Chicot Counties. Scenario 3 indicates overall reduction in depth and extent of the cones of depression of those in scenario 2, and the number of dry cells are only about two-thirds that of dry cells in scenario 2.

April 13, 2004

Available on line.

The Mississippi River Valley alluvial aquifer is a water-bearing assemblage of gravels and sands that underlies about 32,000 square miles of Missouri, Kentucky, Tennessee, Mississippi, Louisiana, and Arkansas. Because of the heavy demands placed on the aquifer, several large cones of depression have formed in the potentiometric surface, resulting in lower well yields and degraded water quality in some areas. A ground-water flow model of the alluvial aquifer was previously developed for an area covering 3,826 square miles, extending south from the Arkansas River into the southeastern corner of Arkansas, parts of northeastern Louisiana, and western Mississippi. The flow-model results indicated that continued ground-water withdrawals at rates commensurate with those of 1997 could not be sustained indefinitely without causing water levels to decline below half the original saturated thickness of the aquifer.

Conjunctive-use optimization modeling was applied to the flow model of the alluvial aquifer to develop withdrawal rates that could be sustained relative to the constraints of critical ground-water area designation. These withdrawal rates form the basis for estimates of sustainable yield from the alluvial aquifer and from rivers specified within the alluvial aquifer model. A management problem was formulated as one of maximizing the sustainable yield from all ground-water and surface-water withdrawal cells within limits imposed by plausible withdrawal rates, and within specified constraints involving hydraulic head and streamflow. Steady-state conditions were selected because the maximized withdrawals are intended to represent sustainable yield of the system (a rate that can be maintained indefinitely).

One point along the Arkansas River and one point along Bayou Bartholomew were specified for obtaining surface-water sustainable-yield estimates within the optimization model. Streamflow constraints were specified at two river cells based on average 7-day low flows with 10-year recurrence intervals.

Sustainable-yield estimates were affected by the allowable upper limit on withdrawals from wells specified in the optimization model. Withdrawal rates were allowed to increase to 200 percent of the withdrawal rate in 1997. As the overall upper limit is increased, the sustainable yield generally increases. Tests with the optimization model show that without limits on pumping, wells adjacent to sources of water, such as large rivers, would have optimal withdrawal rates that were orders of magnitude larger than rates corresponding to those of 1997. Specifying an upper withdrawal limit of 100 percent of the 1997 withdrawal rate, the sustainable yield from ground water for the entire study area is 70.3 million cubic feet per day, which is about 96 percent of the amount withdrawn in 1997 (73.5 million cubic feet per day). If the upper withdrawal limit is increased to 150 percent of the 1997 withdrawal rate, the sustainable yield from ground water for the entire study area is 80.6 million cubic feet per day, which is about 110 percent of the amount withdrawn in 1997. If the upper withdrawal limit is increased to 200 percent of the 1997 withdrawal rate, the sustainable yield from ground water for the entire study area is 110.2 million cubic feet per day, which is about 150 percent of the amount withdrawn in 1997. Total sustainable yield from the Arkansas River and Bayou Bartholomew is about 4,900 million cubic feet per day, or about 6,700 percent of the amount of ground-water withdrawn in 1997. The large, sustainable yields from surface water represent a potential source of water that could supplement ground water and meet the total water demand.

Unmet demand (defined as the difference between the optimized withdrawal rate or sustainable yield, and the anticipated demand) was calculated using different demand rates based on multiples of the 1997-withdrawal rate. Assuming that demand is the 1997 withdrawal rate, and that sustainable-yield estimates are those obtained using upper limits of withdrawal rates of 100-, 150-, and 200-percent of 1997 withdrawal rates, then the resulting unmet demand for the entire model area is 3.3, -7.1, and -36.6 million cubic feet per day, respectively. Whereas, if the demand is specified as 100-, 150-, and 200-percent of the 1997 withdrawal rate, and the sustainable-yield estimates remain the same, then the resulting unmet demand for the entire model area is 3.3, 29.7, and 36.9 million cubic feet per day.

April 13, 2004

other Fact Sheet 072-03. NEBRASKA.

Is septic waste affecting drinking water from shallow domestic wells along the Platte River in eastern Nebraska?. By Ingrid M. Verstraeten, Greg S. Fetterman, Sonja K. Sebree, Michael T. Meyer, and Thomas D. Bullen, 4 pages.

Available from the U.S. Geological Survey Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Fact Sheet 072-03, 4 p., 5 figs.

Available on line.

More than 100 million people in the United States use ground water as their source of drinking water, and about one-third of the rural and waterfront population in the U.S. uses septic systems for wastewater disposal. Septic tanks serve primarily as settling chambers removing solids from the sewage. In sand and gravel aquifers characterized by large pore sizes that allow for relatively easy and rapid transport of water and contaminants, concentrated plumes of dissolved constituents from septic systems can occur in the shallow part of the aquifer and can affect the quality of drinking water withdrawn from domestic wells. In Nebraska, a large number of shallow sand-point wells are used to obtain drinking water in private households, even though their construction for consumptive uses has been banned since 1987. Sand-point and cased wells within 15 feet of septic systems are used for drinking-water supplies in a few cases.

A study conducted by the U.S. Geological Survey, in cooperation with the Lower Platte South Natural Resources District (NRD), the Lower Platte North NRD, the Papio-Missouri River NRD, and the Lower Platte River Corridor Alliance, was done in 2001 and 2002 to assess the quality of drinking water from shallow domestic wells potentially affected by seepage from septic systems. Water samples were analyzed for traces of certain substances that indicate the presence of water and constituents from septic systems. This fact sheet summarizes the results of the study.

April 13, 2004

other SIR2004-5003. CALIFORNIA.

Method of Analysis by the U.S. Geological Survey California District Sacramento Laboratory. Determination of Trihalomethane Formation Potential, Method Validation, and Quality-Control Practices. By Kathryn M. Crepeau, Miranda S. Fram, and Noel Bush, 27 pages.

On-line only.

Available on line.

An analytical method for the determination of the trihalomethane formation potential of water samples has been developed. The trihalomethane formation potential is measured by dosing samples with chlorine under specified conditions of pH, temperature, incubation time, darkness, and residual-free chlorine, and then analyzing the resulting trihalomethanes by purge and trap/gas chromatography equipped with an electron capture detector. Detailed explanations of the method and quality-control practices are provided. Method validation experiments showed that the trihalomethane formation potential varies as a function of time between sample collection and analysis, residual-free chlorine concentration, method of sample dilution, and the concentration of bromide in the sample.

April 8, 2004

WDR ND-03-2. NORTH DAKOTA.

Water Resources Data North Dakota Water Year 2003 Volume 2. Ground Water. By S.M. Robinson and J.D. Wald, 210 pages.

National Technical Information Service Springfield, VA 22161

Available on line.

Water-resources data for the 2003 water year for North Dakota consists of records of discharge, stage, and water quality for streams; contents, stage, and water quality for lakes and reservoirs; and water levels and water quality for ground-water wells. Volume 2 contains water-level records for 136 ground-water wells and water-quality records for 63 monitoring wells. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating Federal, State, and local agencies in North Dakota.

April 2, 2004

WRI 03-4183. NEW JERSEY, NEW YORK, and PENNSYLVANIA.

Total mercury and methylmercury in fish fillets, water, and bed sediments from selected streams in the Delaware River Basin, New Jersey, New York, and Pennsylvania, 1998-2001. By Robin A. Brightbill, Karen Riva-Murray, Michael D. Bilger, and John D. Byrnes, 30 pages.

Available from the USGS Pa. District office, 215 Limekiln Road, New Cumberland, PA 17070 (phone 717-730-6900), at Information Services, Box 25286, Denver Federal Center, Denver, Colo. 80225; and at the USGS libraries in Reston, Va., Denver, Colo., and Menlo Park, Calif.

Available on line.

Within the Delaware River Basin, fish-tissue samples were analyzed for total mercury (tHg). Water and bed-sediment samples were analyzed for tHg and methylmercury (MeHg), and methylation efficiencies were calculated. This study was part of a National Mercury Pilot Program conducted by the U.S. Geological Survey (USGS). The Delaware River Basin was chosen because it is part of the USGS National Water-Quality Assessment Program that integrates physical, chemical, and biological sampling efforts to determine status and trends in surface-water and ground-water resources.

Of the 35 sites in the study, 31 were sampled for fish. The species sampled at these sites include smallmouth bass (Micropterus dolomieu), the target species, and where smallmouth bass could not be collected, brown trout (Salmo trutta), chain pickerel (Esox niger), largemouth bass (Micropterus salmoides), and rock bass (Ambloplites rupestris). There were a total of 32 fish samples; 7 of these exceeded the 0.3 ug/g (micrograms per gram) wet-weight mercury (Hg) concentration set for human health by the U.S. Environmental Protection Agency and 27 of these exceeded the U.S. Fish and Wildlife Service criteria of 0.1 ug/g wet weight for the protection of fish-eating birds and wildlife.

Basinwide analysis of Hg in fish, water, and bed sediment showed tHg concentration in fillets correlated positively with population density, urban land cover, and impervious land surface. Negative correlations included wetland land cover, septic density, elevation, and latitude. Smallmouth bass from the urban sites had a higher median concentration of tHg than fish from agricultural, low intensity-agricultural, or forested sites. Concentrations of tHg and MeHg in water were higher in samples from the more urbanized areas of the basin and were positively correlated with urbanization and negatively correlated with forested land cover. Methylation efficiency of water was negatively correlated with urbanization. Bed-sediment patterns were similar to those observed in water. Concentrations of tHg were higher in samples from the urbanized areas. In the more forested areas, MeHg concentrations were higher than in other land-use areas. Concentrations of tHg in bed sediment were positively correlated with urbanization factors (population, urban land cover, and impervious land surface) and negatively correlated with forested land cover and elevation. Forested land cover and latitude were positively correlated with concentrations of MeHg. The methylation efficiency was higher in samples from the forested areas and was negatively correlated with urbanization.

Analyses within land-use groups showed that tHg concentrations in fish fillets from the urban sites were positively correlated with forested land cover and wetland cover. Urbanization factors within the agricultural group were positively correlated with tHg in fish; concentrations of tHg in fish from sites in the low intensity-agricultural group were negatively correlated with urbanization factors. Within the agricultural land-use group, tHg concentrations in water were negatively correlated with septic density, and MeHg concentrations were negatively correlated with elevation. In the forested and low intensity-agricultural groups, MeHg in water was negatively correlated with forested and agricultural land cover. Methylation efficiency in water also was negatively correlated with forested land cover but positively correlated with agricultural land cover. Bed sediment concentrations of tHg in the forested and low-agricultural groups were positively correlated with agricultural land cover and negatively correlated with forested land cover. Concentrations of MeHg in bed sediment were positively correlated with septic density and drainage area and negatively correlated with forested land cover. Methylation efficiency was negatively correlated with population density, agricultural land cover, and sulfate concentrations in water.

An urbanization effect was observed in all three media--fish, water, and bed sediment. Different factors, basinwide and within land-use groups, showed a complex relation. Additional sampling within these land-use groups could help characterize interrelations of Hg in the environment to fish in the Delaware River Basin.

April 2, 2004

WRI 03-4149. INDIANA.

Chemical and Biological Quality of Surface Water at the U.S. Army Atterbury Reserve Forces Training Area near Edinburgh, Indiana, September 2000 through August 2001. By M.R. Risch, 87 pages.

Available through the USGS Indiana District, 5957 Lakeside Boulevard, Indianapolis, IN 46278, phone 317-290-3333 OR through the USGS Branch of Information Services, Box 25286, Federal Center, Denver, CO 80225-0286.

Available on line.

A base-wide assessment of surface-water quality at the U.S. Army Atterbury Reserve Forces Training Area near Edinburgh, Indiana, examined short-term and long-term quality of surface water flowing into, across, and out of a 33,760-acre study area. The 30-day geometric-mean concentrations of fecal-indicator bacteria (Escherichia coli) in water samples from all 16 monitoring sites on streams in the study area were greater than the Indiana recreational water-quality standard. None of the bacteria concentrations in samples from four lakes exceeded the standard. Half the samples with bacteria concentrations greater than the single-sample standard contained chemical tracers potentially associated with human sewage. Increased turbidity of water samples was related statistically to increased bacteria concentration. Lead concentrations ranging from 0.5 to 2.0 micrograms per liter were detected in water samples at seven monitoring sites. Lead in one sample collected during high-streamflow conditions was greater than the calculated Indiana water-quality standard. With the ex-ception of Escherichia coli and lead, 211 of 213 chemical constituents analyzed in water samples did not exceed Indiana water-quality standards. Out of 131 constituents analyzed in streambed-sediment and fish-tissue samples from three sites in the Common Impact Area for weapons training, the largest concentrations overall were detected for copper, lead, man-ganese, strontium, and zinc. Fish-community integrity, based on diversity and pollution tolerance, was rated poor at one of those three sites. Compared with State criteria, the fish-community data indicated 8 of 10 stream reaches in the study area could be categorized as "fully supporting" aquatic-life uses.

April 1, 2004

Scientific Investigations Report (SIR) 2004-5013. NEBRASKA.

Characterization of ground-water quality, Upper Republican Natural Resources District, Nebraska, 1998-2001. By Jill D. Frankforter and Daniele T. Chafin, 24 pages

Available from the U.S. Geological Survey Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS SIR 2004-5013, 24 p., 1 CD-ROM.

Available on line.

Nearly all rural inhabitants and livestock in the Upper Republican Natural Resources District (URNRD) in southwestern Nebraska use ground water that can be affected by elevated nitrate concentrations. The development of ground-water irrigation in this area has increased the vulnerability of ground water to the introduction of fertilizers and other agricultural chemicals. In 1998, the U.S. Geological Survey, in cooperation with the URNRD, began a study to characterize the quality of ground water in the URNRD area with respect to physical properties and concentrations of major ions, coliform bacteria, nitrate, and pesticides, and to assess the presence of nitrogen concentrations in the unsaturated zone. At selected well sites, the ground-water characterization also included tritium and nitrogen-isotope analyses to provide information about the approximate age of the ground water and potential sources of nitrogen detected in ground-water samples, respectively.

In 1998, ground-water samples were collected from 101 randomly selected domestic well sites. Of the 101 samples collected, 26 tested positive for total coliform bacteria, exceeding the U.S. Environmental Protection Agency's Maximum Contaminant Level (MCL) of zero colonies. In 1999, ground-water samples were collected from 31 of the 101 well sites, and 16 tested positive for coliform bacteria.

Nitrates were detected in ground-water samples from 99 percent of the domestic and irrigation wells sampled from 1998 to 2001. Seven percent of the domestic-well samples and 2 percent of the irrigation-well samples had nitrate concentrations exceeding the U.S. Environmental Protection Agency's MCL for drinking water of 10 milligrams per liter. Areas with nitrate concentrations exceeding 6 milligrams per liter, the URNRD's ground-water management-plan action level, were found predominantly in south-central Perkins, western and south-central Dundy, and north-central Chase Counties. Generally, these concentrations were detected in samples from wells located in upland areas with permeable soils and a high percentage of cropland.

In 1999, 34 of the ground-water samples collected from irrigation wells were analyzed for pesticides, and 16 samples (53 percent) had detectable concentrations of at least one pesticide compound. In 2000, all of the 24 irrigation-well samples analyzed had one or more pesticides present at detectable concentrations. In 2001, 11 of 26 domestic-well samples (46 percent) had detectable concentrations. Although the analytical method used during the study was changed to increase the number of pesticides included in the analyses, the pesticides detected in the ground-water samples were limited to the commonly used herbicide compounds acetochlor, alachlor, atrazine, metolachlor, prometon, propachlor, propazine, trifluralin, and the atrazine degradation product deethylatrazine. Of the compounds detected, only atrazine (3.0 micrograms per liter (µg/L)) and alachlor (2.0 µg/L) have MCLs established by the U.S. Environmental Protection Agency. None of the ground-water samples from the URNRD study area had concentrations that exceeded either MCL.

Tritium age-dating analyses indicate water from one-third of the sites entered the ground-water system prior to 1952. Because the increase in agricultural practices occurred during the 1950s and 1960s, it can be assumed that this water was not influenced by agricultural practices. Nitrogen-isotope speciation analyses for samples from three irrigation wells indicated that the source of nitrates in the ground water is synthetic fertilizer; however, the source at most irrigation wells probably is either naturally occurring or a mixture of water from various anthropogenic sources (such as synthetic fertilizer and animal waste).

April 1, 2004

WRI 03-4310. MAINE.

Drought Conditions in Maine, 1999-2002: A Historical Perspective. By Pamela J. Lombard, 36 pages.

Copies available
Maine Distict
196 Whitten Road
Augusta, Maine 04330

and

U.S. Geological Survey
Information Services
Building 810
Box 25286, Federal Center
Denver, CO 80225

Available on line.

Hydrologic drought can be defined as reduced streamflow, declining ground-water levels, and (or) reductions in lake or reservoir levels. Monthly precipitation totals, annual 7-day low-flow surface-water recurrence intervals, and month-end ground-water levels from drought years 1999-2002 show that 1999-2002 was the driest period of hydrologic drought in more than 50 years of record in Maine. Record lows were set in all three data sets at select locations in central Maine in April 1999, and in September 2001 and 2002. Although streamflows recovered to normal levels during 2000, ground-water levels in central Maine indicate that the drought carried over through 2000 into 2001 and 2002 in some locations.

In 2001, annual 7-day low flows with greater than 100-year recurrence intervals were recorded in central Maine and low flows with up to 75-year recurrence intervals were recorded in coastal areas. In 2002, annual 7-day low flows with greater than 100-year recurrence intervals were recorded at 4 of 14 stations analyzed statewide, placing it as the driest single year of hydrologic drought on record. Month-end ground-water levels at one location in central Maine indicate that the recent hydrologic drought years were the most severe in more than 50 years in that region. The period from 1947 to 1950 may have been the only comparable period of drought to the 1999-2002 period, in Maine. The 1960s drought, although extreme in the far northern and far southern regions of the State, was most exceptional for its duration from 1963 to 1969.

April 1, 2004

WRIR 03-4116. Virginia.

Water and Streambed Sediment Quality, and Ecotoxicology of a Stream along the Blue Ridge Parkway, Adjacent to a Closed Landfill, near Roanoke, Virginia: 1999 by Donna B. Ebner, Donald S. Cherry, and Rebecca J. Currie 55 p.

Available from the Branch of Information Services, Box 25286, Federal Center, Denver CO 80225, U.S. Geological Survey Water-Resources Investigations Report 03-4116, 55 p.

Available on-line.

A study was done of the effects of a closed landfill on the quality of water and streambed sediment and the benthic macroinvertebrate community of an unnamed stream and its tributary that flow through Blue Ridge Parkway lands in west-central Virginia. The primary water source for the tributary is a 4-inch polyvinyl chloride (PVC) pipe that protrudes from the slope at the base of the embankment bordering the landfill. An unusual expanse of precipitate was observed in the stream near the PVC pipe. Stream discharge was measured and water and streambed sediment samples were collected at a nearby reference site and at three sites downstream of the landfill in April and September 1999. Water samples were analyzed for major ions, nitrate, total and dissolved metals, total dissolved solids, total organic carbon, and volatile and semivolatile organic compounds, including organochlorine pesticides and polychlorinated biphenyls (PCBs). Streambed sediment samples were analyzed for total metals, total organic carbon, percent moisture, and volatile and semivolatile organic compounds, including organochlorine pesticides and PCBs.

The benthic macroinvertebrate community within the stream channel also was sampled at the four chemical sampling sites and at one additional site in April and September. Each of the five sites was assessed for physical habitat quality. Water collected periodically at the PVC pipe discharge between November 1998 and November 1999 was used to conduct 48-hour acute and 7-day chronic toxicity tests using selected laboratory test organisms. Two 10-day chronic toxicity tests of streambed sediments collected near the discharge pipe also were conducted.

Analyses showed that organic and inorganic constituents in water from beneath the landfill were discharged into the sampled tributary. In April, 79 percent of inorganic constituents detected in water had their highest concentrations at the site closest to the landfill; at the same site, 59 percent of inorganic constituents detected in streambed sediments were at their lowest concentration. The low dissolved-oxygen concentration and relatively low pH in ground water from beneath the landfill probably had a direct effect on the solubility of metals and other constituents, resulting in the high concentration of inorganic constituents in water, low concentration in sediment, and the development of the precipitate. Most constituents in water in April were progressively lower in concentration from the landfill site downstream. The highest concentrations for 59 percent of constituents detected in sediment were at the farthest downstream site, suggesting that the inorganic constituents came out of solution as the stream water was exposed to the atmosphere. In September, 52 percent of inorganic constituents detected in water were at their highest concentrations at the site nearest the landfill. Of inorganic constituents detected in streambed sediments in September, 60 percent were at their highest concentrations near the landfill. A storm that occurred a few days prior to the September sampling probably affected the preceding steady-state conditions and the distribution of constituents in sediment along the stream. Concentrations of many inorganic constituents in water remained elevated at the farthest downstream site in comparison to the reference site in April and September, indicating that concentrations did not return to background concentrations. In April and September, most of the 17 organic compounds detected in water, including volatile organic and semivolatile organic compounds, were collected in samples near the landfill, and most concentrations were below their respective reporting limits. Probably because of their volatility, few organic compounds were detected at sites downstream of that site. A total of 17 discrete organic compounds were detected in sediment samples in either April or September, including trichloroethene and tetrachloroethene along with their degradation products, 1, 1-dichloroethane and 1,2-dichloroethene; and 4, 4' DDT.

All benthic macroinvertebrate community metrics indicated significantly better conditions at the reference site in comparison to the site nearest the landfill. At the reference site and at three other sites, the taxa collected included several macroinvertebrates that would normally be found under good stream-quality conditions; those collected at the site near the landfill comprised primarily very tolerant macroinvertebrates, including snails, oligochaetes, and a pollution-tolerant dipteran.

The reaction of test organisms to samples of the water discharged from the PVC pipe showed acute toxicity in 10 out of 11 independent tests from November 1998 to November 1999. Organism mortality was observed in every acute test at 100-percent sample strength, and a 48-hr LC₅₀ (the lethal concentration that causes 50-percent mortality of the test organisms after a defined period of exposure) was exceeded 89 percent of the time. Chronic toxicological impairment was reported for Ceriodaphnia dubia with survival and reproduction impaired at 50- and 25-percent concentration of the sample water, respectively. No impairment occurred at 12.5-percent concentration. Overall, the three most notable factors indicating stressed and (or) impacted conditions in the stream near the landfill consisted of (1) the layer of fine metal oxide precipitate in the streambed at and below the site nearest the landfill; (2) the significantly depressed numbers of benthic macroinvertebrate fauna, particularly of sensitive or pollution-intolerant groups; and (3) the consistent acute toxicity of water to Ceriodaphnia dubia.

March 30, 2004

WRI 2004-5039. OKLAHOMA.

Reconnaissance of Surface-Water Quality and Possible Sources of Nutrients and Bacteria in the Turkey Creek Watershed, Northwest Oklahoma, 2002-03. By Carol J. Becker, 24 pages.

This is an On-Line Only report.
Available on line.

The U.S. Geological Survey in cooperation with the Oklahoma Department of Environmental Quality and the U.S. Environmental Protection Agency investigated the distribution of surface-water quality and possible sources of nutrients and Escherichia coli bacteria to surface water in Turkey Creek, which flows about 70 miles through mostly rural agricultural areas in northwest Oklahoma. Results show that discharge on the main stem of Turkey Creek increased during low-flow conditions from an average of 5.4 cubic feet per second at the upper most site to 39 cubic feet per second at the lower most site in the watershed, indicating that Turkey Creek gains water from ground-water discharge. A portion of the increase in stream discharge may be from discharges of treated effluent from city sewage lagoons. However, the volume and frequency of discharges are unknown.

Surface-water-quality samples show that specific conductance ranged from 1,180 to 1,740 microsiemens per centimeter at 25 degrees Celsius during low-flow conditions and in general, decreased downstream with site 1 or site 2 having the largest measurement and site 5 having the lowest. The pH values were slightly alkaline and ranged from 6.8 to 8.5 with a median of 8.2. Dissolved oxygen ranged from 9.3 to 15.9 milligrams per liter in samples collected in the months of November, February, and March and ranged from 5.3 to 13.9 milligrams per liter in samples collected in the months of June, July, and August.

Surface-water-quality samples show that the median concentrations of nitrite plus nitrate as nitrogen (1.16 milligrams per liter) and total phosphorus (0.275 milligram per liter) are larger than the average median concentrations of 0.35 and 0.083 milligram per liter, respectively, calculated from water-quality sites in Oklahoma and part of Arkansas (excluding sites in the Ozark Highland and the Ouachita Mountains ecoregions) having similar stream orders and stream slopes. Concentrations of nitrite plus nitrate as nitrogen increased slightly in the winter months and decreased in the summer months, whereas, concentrations of total phosphorus and orthophosphate as phosphorus tended to increase during the summer months and decrease in the winter months. During high-flow conditions total phosphorus increased 7.7 times above the average concentration of 0.261 milligram per liter in low-flow samples. Orthophosphate concentrations increased 3.5 to 4 times during high-flow conditions.

Almost all low-flow samples showed d15N values between 4 and 10 parts per thousand, above the range for atmospheric nitrogen and synthetic fertilizer and below the range for animal waste. These samples may represent a mixture of nitrate from these two sources and other sources enriched with d15N, such as soils and plants.

Results of the bacterial source tracking indicated that the two source groups having the greatest number of ribopattern matches with surface-water isolates were the cattle group, 53 isolates or 23.5 percent, and the human group, 41 isolates or 18.2 percent. Fewer surface-water isolates matched the deer and horse groups, 8.0 percent and 3.5 percent, respectively. About 43 percent or 96 surface-water isolates were not matched to any source group.

March 24, 2004

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Scientific Investigations Report 2004-5007, 29 p., 10 figs., and 6 tables.

Available on line.

The Buffalo River and its tributary, Calf Creek, are in the White River Basin in the Ozark Plateaus physiographic province in north-central Arkansas. A better understanding of the hydrology and water quality of Calf Creek is of interest to many, including the National Park Service, which administers the Buffalo National River, to evaluate its effect on the hydrology and water quality of the Buffalo River. The streamflow and water-quality characteristics of Calf Creek near Silver Hill, Arkansas, were compared to two sites on the Buffalo River upstream (near Boxley, Arkansas) and downstream (near St. Joe, Arkansas) from the confluence of Calf Creek for calendar years 2001 and 2002. Annual and seasonal loads were estimated for Calf Creek for nutrients, dissolved organic carbon, and suspended sediment and compared with loads at sites on the Buffalo River. Flow-weighted concentrations and yields were computed from estimated annual loads for comparison with other developed and undeveloped basins.

Streamflow varied annually and seasonally at the three sites. The Buffalo River near St. Joe had the largest annual mean streamflow (805 to 1,360 cubic feet per second for 2001 and 2002) compared to the Buffalo River near Boxley (106 and 152 cubic feet per second for 2001 and 2002) and Calf Creek (39 and 80 cubic feet per second for 2001 and 2002).

Concentrations of nutrients, suspended sediment, and fecal indicator bacteria generally were greater in samples from Calf Creek than in samples collected from both Buffalo River sites. Bacteria and suspended-sediment concentrations were greater in samples collected during high-flow events at all three sites. The Buffalo River near Boxley had the lowest concentrations for nutrients, suspended sediment, and fecal indicator bacteria.

Estimated annual loads of the nutrients, suspended sediment, and organic carbon for 2001 and 2002 demonstrated substantial variability between the three sites and through time. Estimated loads for nutrients at the Buffalo River near St. Joe were 7 to 27 times the median loads estimated for Calf Creek and suspended sediment loads were as much as 120 times greater. Dissolved organic carbon loads were 16 to 20 times greater at the Buffalo River near St. Joe than for Calf Creek. The Buffalo River near Boxley had the smallest annual loads for all constituents except for suspended sediment, which were slightly greater than suspended sediment loads estimated for Calf Creek. Higher loads would be expected at the Buffalo River near St. Joe because of the larger basin area and larger volume of streamflow. Likewise, estimated loads for all three sites were greater during seasons that had greater streamflow than during seasons with more frequent periods of base-flow conditions. The highest daily loads occurred in the fall and winter of 2001 and the winter and spring of 2002.

Flow-weighted concentrations generally were higher for Calf Creek than concentrations for the two sites on the Buffalo River and for typical flow-weighted concentrations found in undeveloped basins. However, the flow-weighted concentrations were lower than concentrations in a developed basin.

Annual yields calculated for Calf Creek were higher than the two sites on the Buffalo River and sites that are representative of undeveloped basins but lower than a site representative of a developed basin. The Buffalo River near Boxley had yields that were less than the yields typical of undeveloped basins.

March 23, 2004

WRI 03-4308. MONTANA.

Methods for Estimating Flood Frequency in Montana Based on Data through Water Year 1998. By Charles Parrett and D.R. Johnson, 101 pages.

U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4308, 101 p, 13 figs.

Annual peak discharges having recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years (T-year floods) were determined for 660 gaged sites in Montana and in adjacent areas of Idaho, Wyoming, and Canada, based on data through water year 1998. The updated flood-frequency information was subsequently used in regression analyses, either ordinary or generalized least squares, to develop equations relating T-year floods to various basin and climatic characteristics, equations relating T-year floods to active-channel width, and equations relating T-year floods to bankfull width. The equations can be used to estimate flood frequency at ungaged sites. Montana was divided into eight regions, within which flood characteristics were considered to be reasonably homogeneous, and the three sets of regression equations were developed for each region.

A measure of the overall reliability of the regression equations is the average standard error of prediction. The average standard errors of prediction for the equations based on basin and climatic characteristics ranged from 37.4 percent to 134.1 percent. Average standard errors of prediction for the equations based on active-channel width ranged from 57.2 percent to 141.3 percent. Average standard errors of prediction for the equations based on bankfull width ranged from 63.1 percent to 155.5 percent. In most regions, the equations based on basin and climatic characteristics generally had smaller average standard errors of prediction than equations based on active-channel or bankfull width. An exception was the Southeast Plains Region, where all equations based on active-channel width had smaller average standard errors of prediction than equations based on basin and climatic characteristics or bankfull width.

Methods for weighting estimates derived from the basin- and climatic-characteristic equations and the channel-width equations also were developed. The weights were based on the cross correlation of residuals from the different methods and the average standard errors of prediction. When all three methods were combined, the average standard errors of prediction ranged from 37.4 percent to 120.2 percent. Weighting of estimates reduced the standard errors of prediction for all T-year flood estimates in four regions, reduced the standard errors of prediction for some T-year flood estimates in two regions, and provided no reduction in average standard error of prediction in two regions. A computer program for solving the regression equations, weighting estimates, and determining reliability of individual estimates was developed and placed on the USGS Montana District World Wide Web page. A new regression method, termed Region of Influence regression, also was tested. Test results indicated that the Region of Influence method was not as reliable as the regional equations based on generalized least squares regression.

Two additional methods for estimating flood frequency at ungaged sites located on the same streams as gaged sites also are described. The first method, based on a drainage-area-ratio adjustment, is intended for use on streams where the ungaged site of interest is located near a gaged site. The second method, based on interpolation between gaged sites, is intended for use on streams that have two or more streamflow-gaging stations.

March 19, 2004

WRI 03-4284. ARKANSAS.

Status of water levels in aquifers in the Nacatoch Sand of southwestern and northeastern Arkansas and the Tokio Formation of southwestern Arkansas, 2002. By T.P. Schrader Rheannon M. Scheiderer, 24 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4284, 24 p., 10 figs., 2 tables

Available on line.

Aquifers in the Nacatoch Sand and Tokio Formation in southwestern Arkansas and the Nacatoch Sand in northeastern Arkansas are sources of water for industrial, public supply, domestic, and agricultural uses. Potentiometric-surface maps were constructed from water-level measurements made in 60 wells completed in the Nacatoch Sand and 48 wells completed in the Tokio Formation during January and February 2002.

In northeastern Arkansas, withdrawals from the Nacatoch Sand increased by 784 percent from 1965 to 1990 and decreased by 30 percent from 1990 to 2000. In southwestern Arkansas withdrawals from aquifers in the Nacatoch Sand and Tokio Formation increased by 125 percent and 201 percent, respectively, from 1965 to 1980 and decreased by 93 percent and 81 percent, respectively, from 1980 to 2000. Long-term hydrographs were prepared for 13 wells in the study area. Changes in water levels in some wells may be associated with changes in withdrawals from the respective aquifers.

The direction of ground-water flow in the aquifer in the Nacatoch Sand in northeastern Arkansas generally is towards the southeast. The potentiometric high is located along the north and northwestern boundaries of the subarea.

The direction of ground-water flow in the aquifer in the Nacatoch Sand in southwestern Arkansas is towards the south-southeast in Little River, Miller, and Hempstead Counties and to the east-southeast in Nevada and Clark Counties. The potentiometric high is located within the outcrop area in north-central Hempstead County. Cones of depression exist in the aquifer in the Nacatoch Sand in southeastern Hempstead County and in southwestern Clark County.

The direction of ground-water flow in the aquifer in the Tokio Formation in southwestern Arkansas generally is towards the south or southeast. The potentiometric high is located where the aquifer outcrops in the northwestern part of the study area. An area of artesian flow exists in southeastern Pike, northeastern Hempstead, and northwestern Nevada Counties. One apparent cone of depression may exist northwest of Hope in Hempstead County.

March 16, 2004

other FS 2004-3028.

SAM 2.1--A Computer Program for Plotting and Formatting Surveying Data for Estimating Peak Discharges by the Slope-Area Method. By Hortness, J.E, 6 pages.

Available on line.

The U.S. Geological Survey (USGS) measures discharge in streams using several methods. However, measurement of peak discharges is often impossible or impractical due to difficult access, inherent danger of making measurements during flood events, and timing often associated with flood events. Thus, many peak discharge values often are calculated after the fact by the use of indirect methods.

The most common indirect method for estimating peak discharges in streams is the slope-area method. This, like other indirect methods, requires measuring the flood profile through detailed surveys. Processing the survey data for efficient entry into computer streamflow models can be time demanding: SAM 2.1 is a program designed to expedite that process.

The SAM 2.1 computer program is designed to be run in the field on a portable computer. The program processes digital surveying data obtained from an electronic surveying instrument during slope-area measurements. After all measurements have been completed, the program generates files to be input into the SAC (Slope-Area Computation program; Fulford, 1994) or HEC-RAS (Hydrologic Engineering Center-River Analysis System; Brunner, 2001) computer streamflow models so that an estimate of the peak discharge can be calculated.

March 15, 2004

WRI WRIR 03-4274. IDAHO.

Assessment of Fish Assemblages and Minimum Sampling Effort Required to Determine Biotic Integrity of Large Rivers in Southern Idaho. By Maret, T.R., and Ott, D.S, 16 pages.

Available on line Only.

A critical issue surrounding biomonitoring in large rivers (fifth-through seventh-order) is the minimum sampling-reach distance required to collect an adequate number of fish to represent the fish assemblage within a reach. Excessive sampling effort (excessive reach length) is costly in terms of work hours, reduces the number of sites that can be visited, can compromise field-crew safety, can be logistically unfeasible, and can cause unnecessary injury to captured fish. On the other hand, inadequate sampling effort can produce considerable variability in multiple samples collected at a site and may underrepresent the species or river condition present.

During the summer of 2002, the U.S. Geological Survey, in cooperation with the Idaho Department of Environmental Quality, determined the minimum sampling effort required to characterize fish assemblages at 17 large-river sites in southern Idaho. The study was done as part of the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program. Electrofishing methods and multiple gear types were used to collect sample popluations of fish in river reach lengths representing 40 and 100 times the wetted channel width. Minimum sampling effort was assessed by comparing the relation between reach length and the number of species collected, total individuals collected, and final Index of Biotic Integrity (IBI) scores.

Thirty-two species of fish in the families Catostomidae, Centrarchidae, Cottidae, Cyprinidae, Ictaluridae, Percidae, and Salmonidae were collected. Of these, 12 alien species were collected, representing about 38 percent of all species collected during the study.

A reach length of 30 to 40 times the wetted channel width was determined to be sufficient for collecting an adequate number of fish to estimate species richness and evaluate biotic integrity. At most sites, about 250 fish were needed to effectively represent 95 percent of the species present. Fifty-three percent of the sites assessed, using an IBI developed specifically for large Idaho rivers, received scores of less than 50, indicating poor biotic integrity.

March 15, 2004

WRI 03-4215. OHIO.

Hydrologic and Hydraulic Analyses of Selected Streams in Lorain County, Ohio, 2003. By K. Scott Jackson, Chad J. Ostheimer, and Mattew T. Whitehead, 54 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4215, 54 p., 3 figs., plus CD-ROM.

A limited amount of copies are available through the Ohio District Office. Call (614) 430-7700; or E-mail cmeberle@usgs.gov

Available on line.

Hydrologic and hydraulic analyses were done for selected reaches of nine streams in Lorain County, Ohio. To assess the alternatives for flood-damage mitigation, the Lorain County Engineer and the U.S. Geological Survey (USGS) initiated a cooperative study to investigate aspects of the hydrology and hydraulics of the nine streams. Historical streamflow data and regional regression equations were used to estimate instantaneous peak discharges for floods having recurrence intervals of 2, 5, 10, 25, 50, and 100 years. Explanatory variables used in the regression equations were drainage area, main-channel slope, and storage area. Drainage areas of the nine stream reaches studied ranged from 1.80 to 19.3 square miles.

The step-backwater model HEC-RAS was used to determine water-surface-elevation profiles for the 10-year-recurrence-interval (10-year) flood along a selected reach of each stream. The water-surface profile information was used then to generate digital mapping of flood-plain boundaries. The analyses indicate that at the 10-year flood elevation, road overflow results at numerous hydraulic structures along the nine streams.

March 10, 2004

WRI 03-4321. NEVADA.

Secondary mineral deposits and evidence of past seismicity and heating of the proposed repository horizon at Yucca Mountain, Nevada. By Joseph F. Whelan, 12 pages.

Available on line.

The Drift Degradation Analysis (DDA) (BSC, 2003) for the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, describes model simulations of the effects of pre- and post-closure seismicity and waste-induced heating on emplacement drifts. Based on probabilistic seismic hazard analyses of the intensity and frequency of future seismic events in the region (CRWMS M&O;, 1998), the DDA concludes that future seismicity will lead to substantial damage to emplacement drifts, particularly those in the lithophysal tuffs, where some simulations predict complete collapse of the drift walls.

Secondary mineral studies conducted by the U.S. Geological Survey since 1995 indicate that secondary calcite and silica have been deposited in some fractures and lithophysal cavities in the unsaturated zone (UZ) at Yucca Mountain during at least the past 10 million years (m.y.), and probably since the tuffs cooled to less than 100°C. Tuff fragments, likely generated by past seismic activity, have commonly been incorporated into the secondary mineral depositional sequences.

Preliminary observations indicate that seismic activity has generated few, if any, tuff fragments during the last 2 to 4 m.y., which may be inconsistent with the predictions of drift-wall collapse described in the DDA. Whether or not seismicity-induced tuff fragmentation occurring at centimeter to decimeter scales in the fracture and cavity openings relates directly to failure of tuff walls in the 5.5-m-diameter waste emplacement drifts, the deposits do provide a potential record of the spatial and temporal distribution of tuff fragments in the UZ. In addition, the preservation of weakly attached coatings and (or) delicate, upright blades of calcite in the secondary mineral deposits provides an upper limit for ground motion during the late stage of deposition that might be used as input to future DDA simulations. Finally, bleaching and alteration at a few of the secondary mineral sites indicate that they were subjected to heated gases at approximately the temperatures expected from waste emplacement. These deposits provide at least limited textural and mineralogic analogs for waste-induced, high-humidity thermal alteration of emplacement drift wall rocks.

March 9, 2004

OFR 2004-1045. IDAHO; MONTANA; BRITISH COLUMBIA, CANADA.

Surveying Cross Sections of the Kootenai River Between Libby Dam, Montana, and Kootenay Lake, British Columbia, Canada. By Gary J. Barton, Edward H. Moran, Charles Berenbrock, 35 pages.

Available on line.

The declining population of Kootenai River white sturgeon, which was listed as an Endangered Species in 1994, has prompted a recovery team to assess the feasibility of various habitat enhancement scenarios to reestablish white sturgeon populations. As the first phase in this assessment, the U.S. Geological Survey collected stream channel cross-section and longitudinal data during 2002-03 at about 400 locations along the Kootenai River from Libby Dam near Libby, Montana, to where the river empties into Kootenay Lake near Creston, British Columbia, Canada.

Survey control stations with a horizontal and vertical accuracy of less than 0.1 foot were established using a global positioning system (GPS) prior to collection of stream channel cross-section data along the Kootenai River. A total of 245 cross sections were surveyed. Six cross sections upstream from Kootenai Falls were surveyed uing a total station where the river was too shallow or dangerous to navigate by vessel. The remaining 239 cross sections were surveyed by interfacing real-time GPS equipment with an echo sounder to obtain bathymetric data and with a laser rangefinder to obtain streambank data. These data were merged, straightened, ordered, and reduced in size to be useful. Spacing between these cross sections ranged from about 600 feet in the valley flat near Deep Creek and Shorty Island and near bridges to as much as several miles in other areas.

These stream channel cross sections will provide information that can be used to develop hydraulic flow models of the Kootenai River from Libby Dam, Montana, to Queens Bay on Kootenay Lake in British Columbia, Canada.

March 9, 2004

OFR 2004-1027.

Rocky Mountain Snowpack Chemistry at Selected Sites, 2002. By G.P. Ingersoll, M.A. Mast, Leora Nanus, D.J. Manthorne, D.W. Clow, H.M. Handran, J.A. Winterringer, and D.H. Campbell, 15 pages.

Available online only

During spring 2002, the chemical composition of annual snowpacks in the Rocky Mountain region of the Western United States was analyzed. Snow samples were collected at 75 geographically distributed sites extending from New Mexico to Montana. Near the end of the 2002 snowfall season, the snow-water equivalent (SWE) in annual snowpacks sampled generally was below average in most of the region. Regional patterns in the concentrations of major ions (including ammonium, nitrate, and sulfate), mercury, and stable sulfur isotope ratios are presented.

The 2002 snowpack chemistry in the region differed from the previous year. Snowpack ammonium concentrations were higher at 66 percent of sites in Montana compared to concentrations in the 2001 snowpack but were lower at 74 percent of sites in Wyoming, Colorado, and New Mexico. Nitrate was lower at all Montana sites and lower at all but one Wyoming site; nitrate was higher at all but two Colorado sites and higher at all New Mexico sites. Sulfate was lower across the region at 77 percent of sites. The range of mercury concentrations for the region was similar to those of 2001 but showed more variability than ammonium, nitrate, and sulfate concentrations. Concentrations of stable sulfur isotope ratios exhibited a strong regional pattern with values increasing northward from southern Colorado to northern Colorado and Wyoming.

March 1, 2004

other FS-115-03. NEBRASKA.

Use of continuous seismic profiling to differentiate geologic deposits underlying selected canals in central and western Nebraska. By Wade H. Kress, Benjamin J. Dietsch, Gregory V. Steele, Eric A. White, and James C. Cannia, 6 pages.

Available from the U.S. Geological Survey, Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Fact Sheet 115-03, 6 p., 10 figs.

In central and western Nebraska, the Platte River and its underlying alluvial aquifer are vital sources of water for irrigation, power production, and recreation. Scientists and water managers need accurate knowledge of the saturated thickness, or thickness between the water table and less permeable underlying bedrock, of the alluvial aquifer to better understand ground-water movement and interactions between ground water and surface water. Typically, geologic logs and bedrock outcrops are used to map the depth of the bedrock surface. Although geophysical methods have been used to investigate shallow geologic deposits in central and western Nebraska, no investigations had been conducted using water-borne continuous seismic-reflection profiling (CSP) techniques. In 2001, the U.S. Geological Survey and the Nebraska Platte River Cooperative Hydrology Study engaged in a cooperative pilot study to determine if CSP could be used to determine depth to bedrock and the general characteristics of alluvial sediments in the Platte River Basin. This fact sheet (1) describes the methodology used to obtain the CSP records, (2) provides examples of data obtained from CSP surveys, and (3) evaluates the usefulness of the results obtained with the CSP technique.

February 26, 2004

WRI 03-4307. ARKANSAS.

Hydrogeologic characteristics of four public drinking-water supply springs in northern Arkansas. By Joel M. Galloway, 68 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, 68 p., 36 figs., and 14 tables.

Available on line.

In October 2000, a study was undertaken by the U.S. Geological Survey (USGS) in cooperation with the Arkansas Department of Health to determine the hydrogeologic characteristics, including the extent of the recharge areas, for Hughes Spring, Stark Spring, Evening Shade Spring, and Roaring Spring, which are used for public-water supply in northern Arkansas. Information pertaining to each spring can be used to enable development of effective management plans to protect these water resources and public health.

An integrated approach to determine the ground-water characteristics and the extent of the local recharge areas of the four springs incorporated tools and methods of hydrology, structural geology, geomorphology, geophysics, and geochemistry. Analyses of discharge, temperature, and water quality were completed to describe ground-water flow characteristics, source-water characteristics, and connectivity of the ground-water system with surface runoff. Water-level contour maps were constructed to determine ground-water flow directions and ground-water tracer tests were conducted to determine the extent of the recharge areas and ground-water flow velocities.

Hughes Spring supplies water for the city of Marshall, Arkansas, and the surrounding area. The mean annual discharge for Hughes Spring was 2.9 and 5.2 cubic feet per second for water years 2001 and 2002, respectively. Recharge to the spring occurs mainly from the Boone Formation (Springfield Plateau aquifer). Ground-water tracer tests indicate the recharge area for Hughes Spring generally coincides with the surface drainage area (15.8 square miles) and that Hughes Spring is connected directly to the surface flow in Brush Creek.

The geochemistry of Hughes Spring demonstrated variations with flow conditions and the influence of surface-runoff in the recharge area. Calcite saturation indices, total dissolved solids concentrations, and hardness demonstrate noticeable differences with flow conditions reflecting the reduced residence time and interaction of water with the source rock within the ground-water system at higher discharges for Hughes Spring. Concentrations of fecal indicator bacteria also demonstrated a substantial increase during high-flow conditions, suggesting that a non-point source of bacteria possibly from livestock may enter the system. Conversely, nutrient concentrations did not vary with flow and were similar to concentrations reported for undeveloped sites in the Springfield Plateau and Ozark aquifers in northern Arkansas and southern Missouri. Deuterium and oxygen-18 data show that the Hughes Spring discharge is representative of direct precipitation and not influenced by water enriched in oxygen-18 through evaporation. Discharge data show that Hughes Spring is dominated by conduit type ground-water flow, but a considerable component of diffuse flow also exists in the ground-water system. Carbon-13 data indicate a substantial component of the recharge water interacts with the surface material (soil and regolith) in the recharge area before entering the ground-water system for Hughes Spring. Tritium data for Hughes Spring indicate that the discharge water is a mixture of recent recharge and sub-modern water (recharged prior to 1952).

Stark Spring supplies water for the city of Cushman, Arkansas, and the surrounding area. The mean annual discharge for Stark Spring was 0.5 and 1.5 cubic feet per second for water years 2001 and 2002, respectively. The discharge and water-quality data show the ground-water system for Stark Spring is dominated by rapid recharge from surface runoff and mainly consists of a conduit-type flow system with little diffuse-type flow. Analyses of discharge data show that the estimated recharge area (0.79 square mile) is larger than the surface drainage area (0.34 square mile). Ground-water tracer tests and the outcrop of the Boone Formation indicate that most of the recharge area extends outside the surface drainage area.

Similar to Hughes Spring, the geochemistry of Stark Spring varied with flow conditions. Calcite saturation indices, total dissolved solids concentrations, and hardness demonstrate noticeable differences with flow conditions reflecting the reduced residence time and interaction of the recharge water with the source rock at higher discharges for Stark Spring. In contrast to Hughes Spring, concentrations of fecal indicator bacteria demonstrated a decrease during high-flow conditions, and this dilution effect may reflect the lack of pastureland or sources of non-point contamination in the recharge area. Nutrient concentrations did not vary with flow. Nitrite plus nitrate concentrations were less than concentrations reported for undeveloped sites in the Springfield Plateau and Ozark aquifers in northern Arkansas and southern Missouri, and concentrations of phosphorus and orthophosphorus were slightly higher. Tritium data show that the discharge water is a mixture of recent recharge and sub-modern water (recharged prior to 1952).

Recharge to Evening Shade and Roaring Springs originate from water entering geologic formations in the Ozark aquifer. The springs provide the water supply for the communities of Evening Shade and Cherokee Village, respectively, and the surrounding areas. The mean annual discharge for water years 2001 and 2002 for Evening Shade Spring was 1.44 and 1.24 cubic feet per second, respectively. Roaring Spring had an average flow of 5.7 cubic feet per second for the period of record (July 2001 to October 2002). Little variation in discharge and temperature was evident during high-flow events and throughout the monitoring period for both springs, reflecting the contribution of flow from the Ozark aquifer. As a result, a local recharge area could not be delineated, as the area could include relatively remote locations where geologic formations composing the Ozark aquifer are exposed and have sufficient porosity and hydraulic conductivity to convey water that falls as precipitation to the subsurface. Ground-water flow directions also demonstrated regional flow patterns in each study area from water-level contour maps.

Analyses of major ion concentrations for Evening Shade Spring and Roaring Spring indicated that the source water is a calcium bicarbonate type from a dolomitic mineralogy representative of the Ozark aquifer. Nutrient concentrations generally were lower than Hughes and Stark Springs. Fecal indicator bacteria were not detected at Evening Shade Spring and were detected in only one sample from Roaring Spring. Tritium data show that the discharge water for Evening Shade Spring is a mixture of recent recharge and sub-modern water (recharged prior to 1952) and the discharge water for Roaring Spring was of relatively modern age (recharge within less than 5 to 10 years).

February 24, 2004

WRI 03-4199. CALIFORNIA.

Salt-Pond Box Model (SPOOM) and Its Application to the Napa-Sonoma Salt Ponds, San Francisco Bay, California. By Megan L. Lionberger, David H. Schoellhamer, Paul A. Buchanan, and Scott Meyer, 21 pages.

A box model to simulate water volume and salinity of a salt pond has been developed by the U.S. Geological Survey to obtain water and salinity budgets. The model, SPOOM, uses the principle of conservation of mass to calculate daily pond volume and salinity and includes a salt crystallization and dissolution algorithm. Model inputs include precipitation, evaporation, infiltration, and water transfers. Salinity and water-surface-elevation data were collected monthly in the Napa-Sonoma Salt-Pond Complex from February 1999 through September 2001 and were used to calibrate and validate the model. The months when water transfers occurred were known but the magnitudes were unknown, so the magnitudes of water transfers were adjusted in the model to calibrate simulated pond volumes to measured pond volumes for three ponds. Modeled salinity was then compared with measured salinity, which remained a free parameter, in order to validate the model. Comparison showed good correlation between modeled and measured salinity. Deviations can be attributed to lack of water-transfer information. Water and salinity budgets obtained through modeling will be used to help interpret ecological data from the ponds. This model has been formulated to be applicable to the Napa-Sonoma salt ponds, but can be applied to other salt ponds.

February 19, 2004

WRI 03-4228. ILLINOIS, INDIANA, MICHIGAN, OHIO, WISCONSIN.

Arsenic in Midwestern Glacial Deposits--Occurrence and Relation to Selected Hydrogeologic and Geochemical Factors. By Mary Ann Thomas, 36 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4228, 36 p., 16 figs.

A limited amount of copies are available through the Ohio District at no charge. The office phone number is (614) 430-7700. You may also send an e-mail to cmeberle@usgs.gov

Available on line.

Ground-water-quality data collected as part of 12 U.S. Geological Survey National Water-Quality Assessment studies during 1996-2001 were analyzed to (1) document arsenic occurrence in four types of glacial deposits that occur in large areas of the Midwest, (2) identify hydrogeologic or geochemical factors associated with elevated arsenic concentrations, and (3) search for clues as to arsenic source(s) or mechanism(s) of mobilization that could be useful for designing future studies.

Arsenic and other water-quality constituents were sampled in 342 monitor and domestic wells in parts of Illinois, Indiana, Ohio, Michigan and Wisconsin. Arsenic was detected (at a concentration >1 µg/L) in one-third of the samples. The maximum concentration was 84 µg/L, and the median was less than 1 µg/L. Eight percent of samples had arsenic concentrations that exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level (MCL) of 10 µg/L.

Samples were from four aquifer types.confined valley fill, unconfined valley fill, outwash plain, and till with sand lenses. Highest arsenic concentrations were found in reducing waters from valley-fill deposits. In confined valley fill, all waters were reducing and old (recharged before 1953), and almost half of samples had arsenic concentrations greater than the MCL. In unconfined valley fill, redox conditions and ages were varied, and elevated arsenic concentrations were sporadic. In both types of valley fill, elevated arsenic concentrations are linked to the underlying bedrock on the basis of spatial relations and geochemical correlations.

In shallow (<50 ft) till with sand lenses, arsenic was detected in oxic or mixed waters, but concentrations were rarely greater than the MCL. In shallow outwash-plain deposits, arsenic concentrations greater than the MCL were detected in waters that were reducing and young (recharged after 1953).

Although arsenic concentrations were significantly higher in deep wells (>150 ft), all deep wells were from a distinctive aquifer type (confined valley fill). It is not known whether wells at similar depths in other aquifer types would produce waters with similarly high arsenic concentrations.

Correlations of arsenic with fluoride, strontium, and barium suggest that arsenic might be related to epigenetic (Mississippi Valley-type) sulfide deposits in Paleozoic bedrock. Arsenic is typically released from sulfides by oxidation, but in the current study, the highest arsenic concentrations in glacial deposits were detected in reducing waters. Therefore, a link between epigenetic sulfides and elevated arsenic concentrations in glacial deposits would probably require a multi-step process.

February 19, 2004

other Fact Sheet 110-03. NEW MEXICO, COLORADO.

Sources of water to the Rio Grande upstream from San Marcial, New Mexico. By Stephanie J. Moore, Scott K. Anderholm, Tara Williams-Sether, and John M. Stomp, 6 pages.

Available from U.S. Geological Survey Information Services, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Fact Sheet 110-03, or from the USGS New Mexico District Office, Publications Unit, 5338 Montgomery Blvd. NE, Suite 400, Albuquerque, NM 87109.

February 17, 2004

WRI 03-4261. IDAHO.

Estimating the Magnitude of Bankfull Flows for Streams in Idaho. By Hortness, J.E., and Berenbrock, Charles, 36 pages.

Available on line.

Methods for estimating magnitudes of peak flows with recurrence intervals of 1.5 and 2.33 years were developed for ungaged sites on streams throughout Idaho. These peak flows represent the magnitudes at and near bankfull stage and are needed for quantification of water rights required to maintain or restore fish and wildlife habitats and riparian vegetation. Data from a previous report detailing methods for estimating magnitudes with recurrence intervals of 2 to 500 years were used in this study.

Generalized least-squares regression techniques were used to calculate the final coefficients and measures of accuracy for the regression equations for each of nine regions. The equations relate basin and climatic characteristics to peak flows with recurrence intervals of 1.5 and 2.33 years. The basin and climatic characteristics used to develop the equations included drainage area, mean basin elevation, forested area, mean annual precipitation, basin slope, north-facing slopes greater than 30 percent, and slopes greater than 30 percent. Average standard errors of the regression model ranged from + 150 to - 60.1 percent, and average standard errors of prediction ranged from +165 to - 62.2 percent. The range of prediction errors was narrowest, - 48.9 to - 32.9 percent, for region 5.

A computer program was developed to automate the calculations required for the regional regression calculations. Results from this program comprised calculated peak flows, site-specific standard errors of prediction, and the 90-percent confidence intervals for the estimates.

February 11, 2004

WRI 03-4216. SOUTHWESTERN OHIO.

Pesticides and Pesticide Degradates in the East Fork Little Miami River and William H. Harsha Lake, Southwestern Ohio, 1999-2000. By Jason M Funk, David C. Reutter, Gary L. Rowe, Jr, 16 pages.

Hard copies are available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Report 03-4216, 16 p., 7 figs.

A limited amount of copies are available through the Ohio District Office. Please call (614) 430-7700 or e-mail cmeberle@usgs.gov

Available on line.

In 1999 and 2000, the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program conducted a national pilot study of pesticides and degradates in drinking-water supplies, in cooperation with the U.S. Environmental Protection Agency (USEPA). William H. Harsha Lake, which provides drinking water for several thousand people in southwestern Ohio, was selected as one of the drinking-water supplies for this study. East Fork Little Miami River is the main source of water to Harsha Lake and drains a predominantly agricultural basin. Samples were collected from the East Fork Little Miami River upstream from Harsha Lake, at the drinking-water intake at Harsha Lake, at the outfall just below Harsha Lake, and from treated water at the Bob McEwen Treatment Plant. These samples were analyzed using standardized methods developed for the NAWQA Program.

In all, 42 pesticide compounds (24 herbicides, 4 insecticides, 1 fungicide, and 13 degradates) were detected at least once in samples collected during this study. No compound in the treated water samples exceeded any drinking-water standard, although atrazine concentrations in untreated water exceeded the USEPA Maximum Contaminant Level (MCL) for drinking water (3 µg/L) on four occasions. At least eight compounds were detected with greater than 60 percent frequency at each sampling location. Herbicides, such as atrazine, alachlor, acetochlor, cyanazine, metolachlor, and simazine, were detected most frequently.

Rainfall affected the pesticide concentrations in surface waters of the East Fork Little Miami River Basin. Drought conditions from May through November 1999 led to lower streamflow and pesticide concentrations throughout southwestern Ohio. More normal climate conditions during 2000 resulted in higher streamflows and seasonally higher concentrations in the East Fork Little Miami River and Harsha Lake for some pesticides.

Comparison of pesticide concentrations in untreated lake water and treated drinking water supplied by the Bob McEwen Treatment Plant suggests that treatment processes employed by the plant (chlorination, activated carbon) reduced pesticide concentrations to levels well below USEPA drinking-water standards. In particular, the percentage of pesticides remaining in treated water samples decreased significantly for several frequently occurring pesticides when the plant replaced the use of powdered activated carbon with granular activated carbon in November 1999. For example, the median percentage of atrazine remaining after treatment that included powdered activated carbon was 63 percent, whereas the median percentage of atrazine remaining after the switch to granular activated carbon was 2.4 percent.

February 5, 2004

other Fact Sheet 114-03. NEBRASKA.

Occurrence of pesticides in ground water of the North Platte Natural Resources District, Nebraska, 2002. By Gregory V. Steele and James C. Cannia, 4 pages.

Available from U.S. Geological Survey Information Services, P.O. Box 25286, Denver Federal Center, Denver, CO 80225, USGS Fact Sheet 114-03, 4 p., 3 figs.

Ground water is the source of drinking water for all residents of the North Platte Natural Resources District (NPNRD). Most of the drinking water in the NPNRD comes from unconfined aquifers that are part of the regional High Plains aquifer. The water tables of these local aquifers lie close to the land surface. As a result, the aquifers can be affected by infiltration of irrigation waters that are prone to contain contaminants. Once in the aquifer, contaminants can adversely affect drinking-water supplies.

In 2002, the U.S. Geological Survey and the NPNRD began a cooperative study to determine whether or not 112 pesticides and selected degradation products occur in ground water of the NPNRD. Forty-one monitoring wells at 23 sites throughout the NPNRD were selected for the sampling to determine the areal occurrence of pesticides. This fact sheet summarizes the results of the 2002 sampling.

February 5, 2004

WRI 03-4271. OREGON.

Effect of Water-Column pH on Sediment-Phosphorus Release Rates in Upper Klamath Lake, Oregon, 2001 . By Lawrence H. Fisher and Tamara M. Wood , 20 pages.

Available on line.

Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. Aerial release rates for a stable sediment/water interface that is representative of the sediment surface area to water column volume ratio (1:3) observed in the lake and volumetric release rates for resuspended sediment events were determined at three different pH values (8.1, 9.2, 10.2). Ambient water column pH (8.1) was maintained by sparging study columns with atmospheric air. Elevation of the water column pH to 9.2 was achieved through the removal of dissolved carbon dioxide by sparging with carbon dioxide-reduced air, partially simulating water chemistry changes that occur during algal photosynthesis. Further elevation of the pH to 10.2 was achieved by the addition of sodium hydroxide, which doubled average alkalinities in the study columns from about 1 to 2 milliequivalents per liter.

Upper Klamath Lake sediments collected from the lake bottom and then placed in contact with lake water, either at a stable sediment/water interface or by resuspension, exhibited an initial capacity to take up soluble reactive phosphorus (SRP) from the water column rather than release phosphorus to the water column. At a higher pH this initial uptake of phosphorus was slowed, but not stopped. This initial phase was followed by a reversal in which the sediments began to release SRP back into the water column. The release rate of phosphorus 30 to 40 days after suspension of sediments in the columns was 0.5 µg/L/day (micrograms per liter per day) at pH 8, and 0.9 µg/L/day at pH 10, indicating that the higher pH increased the rate of phosphorus release by a factor of about two. The highest determined rate of release was approximately 10% (percent) of the rate required to explain the annual internal loading to Upper Klamath Lake from the sediments as calculated from a lake-wide mass balance and observed in total phosphorus data collected at individual locations.

February 5, 2004

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4127, 114 p., 50 figs.

Available on line.

Oxidizable materials from the San Joaquin River upstream of Vernalis can contribute to low dissolved oxygen episodes in the Stockton Deep Water Ship Channel that can inhibit salmon migration in the fall. The U.S. Geological Survey collected and analyzed samples at four San Joaquin River sites in July through October 2000 and June through November 2001, and at eight tributary sites in 2001. The data from these sites were supplemented with data from samples collected and analyzed by the University of California at Davis at three San Joaquin River sites and eight tributary sites as part of a separate study. Streamflows in the San Joaquin River were slightly above the long-term average in 2000 and slightly below average in 2001. Nitrate loads at Vernalis in 2000 were above the long-term average, whereas loads in 2001 were close to average. Total nitrogen loads in 2000 were slightly above average, whereas loads in 2001 were slightly below average. Total phosphorus loads in 2000 and 2001 were well below average. These nutrient loads correspond with the flow-adjusted concentration trends.nitrate concentrations significantly increased since 1972 (p < 0.01), whereas total nitrogen and total phosphorus concentrations did not (p > 0.05). Loading rates of nutrients and dissolved organic carbon increased in the San Joaquin River in the fall with the release of wetland drainage into Mud Slough and with increased reservoir releases on the Merced River. During August 2000 and September 2001, the chlorophyll-a loading rates and concentrations in the San Joaquin River declined and remained low during the rest of the sampling period. The most significant tributary sources of nutrients were the Tuolumne River, Harding Drain, and Mud Slough. The most significant tributary sources of dissolved organic carbon were Salt Slough, Mud Slough, and the Tuolumne and Stanislaus Rivers. Compared with nutrients and dissolved organic carbon, the tributaries were minor sources of chlorophyll-a, suggesting that most of the chlorophyll-a was pro duced in the San Joaquin River rather than its tributaries. On the basis of the carbon-to-nitrogen ratios and the d13C of particulate organic matter in the San Joaquin River and tributaries, the particulate organic matter in the river was mostly phytoplankton. On the basis of the d15N values of the particulate organic matter, and of total dissolved nitrogen and nitrate, the nitrate in the San Joaquin River probably was a significant nutrient source for the phytoplankton. The range of d15N and d18O values of nitrate in the San Joaquin River and tributaries suggest that animal waste or sewage was a significant source of nitrate in the river at the time the samples were collected.

The Stockton Deep Water Ship Channel (ship channel) was dredged to a depth of about 35 ft to allow ocean-going ships to reach the inland Port of Stockton (fig. 1). Immediately upstream of the ship channel, the San Joaquin River is about 8 to 10 ft deep. At the beginning of the ship channel and for about 7 mi downstream to Turner Cut (fig. 1), the San Joaquin River annually experiences episodes of low dissolved oxygen (Lee and Jones-Lee, 2003). These episodes are most prolonged and acute in the summer and fall months, but also have been observed in other months. Dissolved oxygen levels typically fall as low as 2.0 to 2.5 mg/L (Christopher Foe, California Regional Water Quality Control Board, Central Valley Region, written commun., 2002). The oxygen deficit can stress and kill resident aquatic life and could inhibit the upstream migration of fall-run Chinook salmon (Lee and Jones-Lee, 2003).

The State's basin plan for the Sacramento-San Joaquin Delta contains a water quality objective requiring oxygen levels to be maintained above 6 mg/L in the San Joaquin River between Stockton and Turner Cut during September through November and above 5 mg/L at all other times (California Regional Water Quality Control Board, 1998). The 6 mg/L objective was adopted to protect the upstream migration of fall-run Chinook salmon. The State of California placed the San Joaquin River on the 303(d) list of impaired water bodies in 1998 because of low dissolved oxygen levels (California State Water Resources Control Board, 1998). The problem was classified as a high priority for correction, and the State committed to complete a technical Total Maximum Daily Load (TMDL) in 2003 and an implementation plan in 2004 (Mark Gowdy, California Regional Water Quality Control Board, Central Valley Region, written commun., 2003). A technical advisory committee was formed to advise the State on the development of the TMDL and to oversee projects funded by the CALFED Bay-Delta Program related to the low dissolved oxygen problem in the lower San Joaquin River.

The conceptual model of the dissolved oxygen impairment in the ship channel incorporates two primary factors.hydrology and upstream loads of oxidizable material. Deepening the river decreased the efficiency of atmospheric reaeration and increased water residence time allowing a larger fraction of the imported organic material to be oxidized. If streamflows from upstream could be increased, it would have two counteracting effects on the problem.it would increase the load of upstream oxidizable material, but it would reduce the water residence time (Mark Gowdy, California Regional Water Quality Control Board, Central Valley Region, written commun., 2003). The main sources of upstream material are the City of Stockton Wastewater Treatment Plant ("WWTP" on fig. 1) about one mile upstream of the ship channel and the upstream San Joaquin Basin (fig. 1). The upstream loads from the San Joaquin Basin appear to have the greatest impact on dissolved oxygen in the ship channel in summer, and they decline in significance in the fall and winter to the City of Stockton discharges of treated wastewater containing high concentrations of ammonia.

The primary purpose of this study was to define the sources and transport of nutrients, organic carbon, and chlorophyll-a in the upstream San Joaquin Basin, above Vernalis. A secondary purpose was to compare nutrient loads and concentrations from the 1970s and 1980s to the present (Kratzer and Shelton, 1998). This study was funded by the CALFED Bay-Delta Program. The sampling in this study was coordinated with an independent study conducted in the study area by the University of California at Davis (UCD). The UCD study was funded by the U.S. Fish and Wildlife Service to evaluate the food resources to the Sacramento-San Joaquin Delta from the Sacramento and San Joaquin Basins.

February 5, 2004

WRI 03-4255. PENNSYLVANIA, NEW JERSEY.

Historical ground-water-flow patterns and trends in iron concentrations in the Potomac-Raritan-Magothy aquifer system in parts of Philadelphia, Pennsylvania, and Camden and Gloucester Counties, New Jersey. By Ronald A. Sloto, 37 pages.

Available from the USGS Pennsylvania District office, 215 Limekiln Road, New Cumberland, PA 17070 (phone 717-730-6900) and at the USGS libraries in Reston, Va., Denver, Colo., and Menlo Park, Calif., U.S. Geological Survey Water-Reesources Investigations Report 03-4255, 37 p., 24 figs.

Available on line.

The Potomac-Raritan-Magothy (PRM) aquifer system is an important sole-source ground-water supply in Camden and Gloucester Counties, N.J. Elevated iron concentrations are a persistent water-quality problem associated with ground water from the PRM. In Philadelphia, the PRM no longer is usable as a water supply because of highly elevated concentrations of iron (as high as 429 mg/L [milligrams per liter]), manganese (as high as 4 mg/L), and sulfate (as high as 1,720 mg/L). A strongly reducing environment in the PRM in south Philadelphia causes these constituents to be remobilized by reductive dissolution of the aquifer matrix.

By the 1920s, ground-water pumping changed the natural ground-water-flow patterns, and ground water flowed toward pumping centers in Philadelphia. By 1940, recharge areas changed from the topographically high areas east of Trenton, N.J., to the outcrop area of the PRM in Philadelphia, and the Delaware River became a source of recharge instead of a point of ground-water discharge. By 1954, the cone of depression caused by pumping at the former Philadelphia Naval Ship Yard (PNSY) exceeded 50 feet below NGVD 29, and the direction of ground-water flow was from New Jersey toward Philadelphia. Because of highly elevated concentrations of iron and manganese, pumping at the former PNSY ceased in the mid-1960s. Beginning about 1951, increased ground-water withdrawals from the PRM in New Jersey reversed the hydraulic gradient so that ground-water flow was from Philadelphia toward New Jersey under the Delaware River, making Philadelphia a recharge area for the PRM aquifer system in parts of Camden and Gloucester Counties. By 1988, water levels in the lower aquifer of the PRM in New Jersey had declined to 103 feet below NAVD 88.

In 1943, dissolved iron concentrations ranged from 0.07 to 0.6 mg/L at the former PNSY. By 1967 when the wells at the PNSY were abandoned, dissolved iron concentrations had reached 46 mg/L. Dissolved iron concentrations in water from industrial wells in Philadelphia increased from 0.17 mg/L in 1949 to 19 mg/L in 1979. The concentration of dissolved iron in water from wells screened in the lower aquifer in New Jersey also increased with time. By 1985, dissolved iron concentrations were as high as 16 mg/L for Eagle Point refinery wells.

January 28, 2004

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4264, 90 p., 10 figs.

Public water-supply systems in Tennessee provide water to meet customer needs for domestic, industrial, and commercial users and municipal services. In 2000, more than 500 public water-supply systems distributed about 890 million gallons per day (Mgal/d) of surface water and ground water to a population of about 5 million in Tennessee. Surface-water sources provided 64 percent (about 569 Mgal/d) of the State.s water supplies, primarily in Middle and East Tennessee. Ground water produced from wells and springs in Middle and East Tennessee and from wells in West Tennessee provided 36 percent (about 321 Mgal/d) of the public water supplies. Springs in Middle and East Tennessee provided about 14 percent (about 42 Mgal/d) of ground-water supplies used in the State. Per capita water use for Tennessee in 2000 was about 136 gallons per day. An additional 146 public water-supply systems provided approximately 84 Mgal/d of water supplies that were purchased from other water systems.

Water withdrawals by public water-supply systems in Tennessee have increased by over 250 percent; from 250 Mgal/d in 1955 to 890 Mgal/d in 2000. Although Tennessee public water-supply systems withdraw less ground water than surface water, ground-water withdrawal rates reported by these systems continue to increase. In addition, the number of public water-supply systems reporting ground-water withdrawals of 1 Mgal/d or more in West Tennessee is increasing.

January 27, 2004

WRI 03-4221. NEW MEXICO.

Effects of channel changes on geomorphic and hydraulic characteristics of the Canadian River near Raton, New Mexico, 1965-2000. By Anne Marie Matherne and Nathan C. Myers, 44 pages.

Available from U.S. Geological Survey Information Services, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4221, 44 p., 15 figs.

Following a 500-year flood in June 1965, New Mexico Highway 555 was constructed in its present (2000) configuration through the Canadian River Valley. During road construction, the river was channelized over several reaches. A 20-year recurrence-interval flood in 1999 damaged several sections of roadway. This study examines how changes in channel morphology associated with channelization may have contributed to damage caused by the 1999 floods by examining how different cross-sectional channel morphologies contribute to the effects of small- (bankfull and flood-prone) and larger (20-year recurrence-interval) magnitude discharges. The results indicate that in channelized reaches, channels that may effectively accommodate small-magnitude floods may be ineffective at containing larger magnitude floods. In addition, the 1999 stream channel overall had deepened since 1965. This deepening was most pronounced upstream from the most flow restrictive of the channelized reaches.

Geomorphologic and hydraulic data were derived from level-survey measurements at 10 channel cross sections and 10 channel slopes on the Canadian River and from digital elevation models developed from aerial photographs taken June 23, 1965, and June 1, 1999. A comparison of data derived from the 1965 and 1999 aerial photographs indicates that the Canadian River channel in the study area was shorter, deeper, steeper, and less sinuous in 1999 than in 1965. Prior to construction of New Mexico Highway 555, the zone of active-channel migration encompassed the entire width of the Canadian River Valley in the upper part of the study area. Streamflow-control structures designed to protect the road from erosion and deep, narrow stream channels built during construction of New Mexico Highway 555 now constrain the channel and have reduced the amplitude and frequency of channel meanders. Major channel modifications include channel straightening and elimination of meanders at cross sections CR4B and CR6B, gabion construction at cross sections CR3 and CR7, and construction of a bridge at cross section CR5.

The Coal Canyon debris-fan deposit, adjacent to the Canadian River channel where it parallels New Mexico Highway 555 downstream from cross section CR7, appears to effectively channelize the Canadian River along this reach, much like the artificially confined channel at cross section CR4. The deposit also causes consequences similar to the channelized reach at cross section CR4 in terms of increased potential sediment-transport capacity at large discharges.

January 21, 2004

WRI 03-4278. VIRGINIA.

Aquifer Susceptibility in Virginia, 1998-2000. By David L. Nelms, George E. Harlow, Jr., L. Niel Plummer, and Eurybiades Busenberg, 58 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4278, 58 p.

Available on line.

The U.S. Geological Survey (USGS), in cooperation with the Virginia Department of Health, sampled water from 171 wells and springs across the Commonwealth of Virginia between 1998 and 2000 as part of the Virginia Aquifer Susceptibility study. Most of the sites sampled are public water supplies that are part of the comprehensive Source Water Assessment Program for the Commonwealth. The fundamental premise of the study was that the identification of young waters (less than 50 years) by multiple environmental tracers could be used as a guide for classifying aquifers in terms of susceptibility to contamination from near-surface sources. Environmental tracers, including chlorofluorocarbons (CFCs), sulfur hexafluoride (SF₆), tritium (³H), and tritium/helium-3 (³H/³He), and carbon isotopes (¹⁴C and δ¹³C) were used to determine the age of water discharging from wells and springs. Concentrations of CFCs greater than 5 picograms per kilogram and ³H concentrations greater than 0.6 tritium unit were used as thresholds to indicate that parts of the aquifer sampled have a component of young water and are, therefore, susceptible to near-surface contamination.

Concentrations of CFCs exceeded the susceptibility threshold in 22 percent of the wells and in one spring sampled in the Coastal Plain regional aquifer systems. About 74 percent of the samples from wells with the top of the first water zone less than 100 feet below land surface exceeded the threshold values, and water supplies developed in the upper 100 feet of the Coastal Plain are considered to be susceptible to contamination from near-surface sources. The maximum depth to the top of the screened interval for wells that contained CFCs was less than 150 feet. Wells completed in the deep confined aquifers in the Coastal Plain generally contain water older than 1,000 years, as indicated by carbon-14 dating, and are not considered to be susceptible to contamination under natural conditions. All of the water samples from wells and springs in the fractured-rock terrains (the Appalachian Plateaus, Valley and Ridge, Blue Ridge, and Piedmont regional aquifer systems) contained concentrations of CFCs and ³H greater than one or both of the thresholds. Because all of the water samples exceeded at least one of the threshold values, young water is present throughout most of these regional aquifer systems; therefore, water supplies developed in these systems are susceptible to contamination from near-surface sources. No relation between well depth and presence of CFCs is evident from samples in the fractured-rock terrains.

More than 95 percent of the samples for which the dating methods were applicable contained waters with apparent ages less than 35 years. About 5 percent of these samples, most of which were from the Blue Ridge and Piedmont regional aquifer systems, contained young waters with apparent ages of less than 5 years. Most of the samples from the Valley and Ridge Carbonate, Blue Ridge, and Piedmont regional aquifer systems had young water fractions of more than 50 percent, whereas samples from the Coastal Plain Shallow and Appalachian Plateaus regional aquifer systems contained less than 40 percent young waters.

Concentrations of CFCs in excess of air-water equilibrium, which can indicate that nonatmospheric sources (such as sewage effluent) have introduced CFCs into the ground-water system, were measured in 6 and 48 percent of the water samples from the Coastal Plain and fractured-rock regional aquifer systems, respectively. The nitrate (NO₃) concentrations greater than the USGS detection level of 0.05 milligrams per liter generally increase as the apparent age of the young water fraction decreases, with the highest NO₃ concentrations for samples in which one or more of the CFCs are above modern atmospheric mixing ratios (commonly referred to as "contaminated" for ground-water dating purposes). Most of the samples in which NO₃ was detected were from the fractured-rock regional aquifer systems, especially the Valley and Ridge Carbonate regional aquifer system, where 90 percent of the samples had concentrations greater than the detection level. Numerous halogenated volatile organic compounds were detected at low concentrations (parts per quadrillion) in the samples from the regional aquifer systems in the fractured-rock terrains and the Coastal Plain Shallow regional aquifer system.

The ratio of the percentage and apparent age of the young fraction in binary mixtures of young and old (greater than 50 years) waters provides an indication of the relative degree of susceptibility. Large ratios are associated with samples in which the fraction of the young water is large (greater than 75 percent) and apparent age is extremely young (less than 5 years). Samples from the fractured-rock regional aquifer systems generally have the largest ratios. Analysis-of-variance tests indicate that the ratios in the samples from the Blue Ridge regional aquifer system are significantly higher (p<0.05) than those in the other regional aquifer systems. Results from the multiple tracer approach indicate that shallow wells (less than 100 feet deep) and springs in the Coastal Plain and wells and springs in the fractured-rock terrains contain a component of young ground water and are, therefore, susceptible to contamination from near-surface sources.

January 21, 2004

WRI 03-4258. VIRGINIA.

Ground-Water Flow and Saline Water in the Shallow Aquifer System of the Southern Watersheds of Virginia Beach, Virginia. By Barry S. Smith, 67 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4258,67 p.

Available on line.

Population and tourism continues to grow in Virginia Beach, Virginia, but the supply of freshwater is limited. A pipeline from Lake Gaston supplies water for northern Virginia Beach, but ground water is widely used to water lawns in the north, and most southern areas of the city rely solely on ground water. Water from depths greater than 60 meters generally is too saline to drink. Concentrations of chloride, iron, and manganese exceed drinking-water standards in some areas. The U.S. Geological Survey, in cooperation with the city of Virginia Beach, Department of Public Utilities, investigated the shallow aquifer system of the southern watersheds to determine the distribution of fresh ground water, its potential uses, and its susceptibility to contamination.

Aquifers and confining units of the southern watersheds were delineated and chloride concentrations in the aquifers and confining units were contoured. A ground-water-flow and solute-transport model of the shallow aquifer system reached steady state with regard to measured chloride concentrations after 31,550 years of freshwater recharge. Model simulations indicate that if freshwater is found in permeable sediments of the Yorktown-Eastover aquifer, such a well field could supply freshwater, possibly for decades, but eventually the water would become more saline. The rate of saline-water intrusion toward the well field would depend on the rate of pumping, aquifer properties, and on the proximity of the well field to saline water sources. The steady-state, ground-water-flow model also was used to simulate drawdowns around two hypothetical well fields and drawdowns around two hypothetical open-pit mines. The chloride concentrations simulated in the model did not approximate the measured concentrations for some wells, indicating sites where local hydrogeologic units or unit properties do not conform to the simple hydrogeology of the model.

The Columbia aquifer, the Yorktown confining unit, and the Yorktown-Eastover aquifer compose the hydrogeologic units of the shallow aquifer system of Virginia Beach. The Columbia and Yorktown-Eastover aquifers are poorly confined throughout most of the southern watersheds of Virginia Beach. The freshwater-to-saline-water distribution probably is in a dynamic equilibrium throughout most of the shallow aquifer system. Freshwater flows continually down and away from the center of the higher altitudes to mix with saline water from the tidal rivers, bays, salt marshes, and the Atlantic Ocean. Fresh ground water from the Columbia aquifer also leaks down through the Yorktown confining unit into the upper half of the Yorktown-Eastover aquifer and flows within the Yorktown-Eastover above saline water in the lower half of the aquifer. Ground-water recharge is minimal in much of the southern watersheds because the land surface generally is low and flat.

January 20, 2004

OFR 03-480. MINNESOTA.

Mercury data from small lakes in Voyageurs National Park, northern Minnesota, 2000-02. By R.M. Goldstein, M.E. Brigham, Luke Steuwe, and M.A. Menheer, 18 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Open-File Report 03-480, 18 p.

Mercury contamination of aquatic ecosystems is a resource concern in Voyageurs National Park. High concentrations of mercury in fish pose a potential risk to organisms that consume large amounts of those fish. During 2000.02, the U.S. Geological Survey measured mercury in water collected from 20 lakes in Voyageurs National Park. Those lakes span a gradient in fish-mercury concentrations, and also span gradients in other environmental variables that are thought to influence mercury cycling. During 2001, near surface methylmercury concentrations ranged from below the method detection limit of 0.04 nanograms per liter (ng/L) to 1.02 ng/L. Near surface total mercury concentrations ranged from 0.34 ng/L to 3.82 ng/L. Hypolimnetic methylmercury ranged from below detection to 2.69 ng/L, and hypolimnetic total mercury concentrations ranged from 0.34 ng/L to 7.16 ng/L. During 2002, near surface methylmercury concentrations ranged from below the method detection limit to 0.46 ng/L, and near surface total mercury ranged from 0.34 ng/L to 4.81 ng/L.

January 20, 2004

WRI 03-4223. MINNESOTA.

Reconnaissance of mercury and methylmercury in the St. Croix River and selected tributaries, Minnesota and Wisconsin, July 2000 through October 2001. By G.A. Payne, and D.S. Hansen, 9 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4223, 9 p.

A reconnaissance-level assessment to characterize total mercury and methylmercury concentrations during summer low-flow conditions was conducted in the St. Croix River Basin during July 2000 through October 2001. Samples were collected at 6 main stem and 16 tributary sites. Loads of total mercury and methylmercury increased in the St. Croix River main stem between Nevers Dam and Franconia. Total mercury and methylmercury concentrations were greatest during July in the Namekagon River. Methylmercury yields in the Namekagon River and Rush Creek were greater than the yield for other tributary streams. Methylmercury concentrations and yields were greater in tributaries draining wetland/forest watersheds than in tributaries draining agricultural/forest watersheds.

January 20, 2004

WRI 03-4201. PENNSYLVANIA.

MTBE concentrations in ground water in Pennsylvania. By Steven D. McAuley, 44 pages.

Available from the USGS Pennsylvania District office, 215 Limekiln Road, New Cumberland, PA 17070 (phone 717-730-6900) and at the USGS libraries in Reston, Va., Denver, Colo., and Menlo Park, Calif., U.S. Geological Survey Water-Resources Investigations Report 03-4201, 44 p., 12 figs., 2 app./

Available on line.

The distribution, concentrations, and detection frequency of methyl tert-butyl-ether (MTBE), a gasoline additive used in reformulated gasoline to improve air quality, were characterized in Pennsylvania's ground water. Two sources of MTBE in ground water, the atmosphere and storage-tank release sites, were examined. An analysis of atmospheric MTBE concentrations shows that MTBE detections (MTBE greater than or equal to 0.2 micrograms per liter) in ground water are more likely the result of storage-tank releases than atmospheric deposition. A comparison of 86 ground-water samples near storage-tank releases and 359 samples from ambient ground water (not thought to be affected by point-source releases of MTBE or BTEX compounds) shows that samples within about 0.5 mile downgradient of storage-tank release sites have significantly greater MTBE detection frequency than ambient ground-water samples.

Aquifer type, land use, and the use of Reformulated Gasoline (RFG) are associated with high rates of occurrence of MTBE in ground water in Pennsylvania. Ground-water samples from wells in crystalline-rock aquifers near storage-tank release sites have a significantly greater MTBE detection frequency (57 percent) compared to other aquifers. Samples from wells in urban areas have a significantly greater MTBE detection frequency compared to ambient samples in agricultural and forested areas. Samples from the RFG-use areas in the five southeastern counties of Pennsylvania have a significantly greater MTBE detection frequency than samples outside of the RFG-use area. MTBE detection frequency of samples near storage-tank release sites in the RFG-use area (45 percent) are significantly greater than ambient samples in the RFG-use area.

January 20, 2004

WRI 03-4297. MINNESOTA.

Application of a revised Local government Annual Reporting System for estimation of non-point source reductions in agricultural watersheds. By G.A. Payne, E.H. Mohring, and R.M. Goldstein, 17 pages.

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 03-4297, 17 p.

The Minnesota Board of Water and Soil Resources uses an algorithm based system called LARS (Local government Annual Reporting System) to estimate the amount of non-point nutrients and sediment prevented from reaching the State.s aquatic systems when new land-use best-management practices are applied. Since the initiation in 1995, LARS has not been updated. The Technical Advisory Committee reviewed significant findings since 1995 for incorporation into the LARS algorithm. These algorithms estimate the amount of sediment and primarily phosphorus retained in a basin as a result of each best-management practice. The program was intended to be simple and small enough to be installed on computers used by local government offices in the mid-1990's. The most important update to the LARS algorithms was a more accurate sediment delivery ratio. The new sediment delivery ratio improved the accuracy of the LARS algorithms.

January 12, 2004

Circular 1243, Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas and Wyoming

Water in Storage and Approaches to Ground-Water Management, High Plains Aquifer, 2000, By McGuire, V.L., Johnson, M.R., Schieffer, R.L., Stanton, J.S., Sebree, S.K., and Verstraeten, I.M., 2003, 51 pages. Free.

The High Plains aquifer underlies one of the major agricultural regions in the world, including parts of eight States.Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water-level declines started to occur in the High Plains aquifer soon after the beginning of extensive ground-water irrigation. In response to the water-level declines, the U.S. Geological Survey, in cooperation with numerous Federal, State, and local water-resource agencies began a monitoring program in 1988 to assess annual water-level change in the aquifer.

Using water-levels from wells measured in predevelopment (the period prior to extensive ground-water irrigation in an area) and wells measured in Spring 2000, the U.S. Geological Survey determined the change in water in storage in the High Plains aquifer from predevelopment to 2000 was a decline of about 200 million acre-feet, a 6-percent decline from the water in storage in the aquifer at predevelopment. Most of the decline in storage has occurred in a 17-million-acre area in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, and Texas with water-level declines of 25 to more than 150 feet; in this area, water in storage in the aquifer has declined about 190 million acre-feet, a 34-percent decline.

The report also includes a summary of approaches to ground-water management in the States overlying the aquifer. These approaches all include the stipulation that the water be used for a reasonable purpose and not wasted. The differences among the approaches include the legal doctrines, which form the basis for ground-water allocations. The legal doctrines used are: prior appropriation, applicable in Colorado, Kansas, New Mexico, South Dakota, and Wyoming; reasonable use, applicable in Nebraska; correlative rights, applicable in Okalahoma; and rule of capture, applicable in Texas.

January 8, 2004

WRI 03-4193. PENNSYLVANIA, MARYLAND, and DELAWARE.

Simulation of streamflow and water quality in the Christina River subbasin and overview of simulations in other subbasins of the Christina River Basin, Pennsylvania, Maryland, and Delaware, 1994-98. By Lisa A. Senior and Edward H. Koerkle, 144 pages.

Available from the USGS Pa. District office, 215 Limekiln Road, New Cumberland, PA 17070 (phone 717-730-6900) and at the USGS libraries in Reston, Va., Denver, Colo., and Menlo Park, Calif., U.S. Geological Survey Water-Resources Investigations Report 03-4193, 144 p., 48 figs., 3 app.

Available on line.

The Christina River Basin drains 565 square miles (mi2) in Pennsylvania and Delaware and includes the major subbasins of Brandywine Creek, Red Clay Creek, White Clay Creek, and Christina River. The Christina River subbasin (exclusive of the Brandywine, Red Clay, and White Clay Creek subbasins) drains an area of 76 mi2. Streams in the Christina River Basin are used for recreation, drinking water supply, and support of aquatic life. Water quality in some parts of the Christina River Basin is impaired and does not support designated uses of the stream. A multi-agency water-quality management strategy included a modeling component to evaluate the effects of point- and nonpoint-source contributions of nutrients and suspended sediment on stream water quality. To assist in nonpoint-source evaluation, four independent models, one for each of the four main subbasins of the Christina River Basin, were developed and calibrated using the model code Hydrological Simulation Program­--Fortran (HSPF). Water-quality data for model calibration were collected in each of the four main subbasins and in small subbasins predominantly covered by one land use following a nonpoint-source monitoring plan. Under this plan, stormflow and base-flow samples were collected during 1998 at two sites in the Christina River subbasin and nine sites elsewhere in the Christina River Basin.

The HSPF model for the Christina River subbasin simulates streamflow, suspended sediment, and the nutrients, nitrogen and phosphorus. In addition, the model simulates water temperature, dissolved oxygen, biochemical oxygen demand, and plankton as secondary objectives needed to support the sediment and nutrient simulations. For the model, the basin was subdivided into nine reaches draining areas that ranged from 3.8 to 21.9 mi2. Ten different pervious land uses and two impervious land uses were selected for simulation. Land-use areas were determined from 1995 land-use data. The predominant land uses in the Christina River subbasin are residential, urban, forested, agricultural, and open.

The hydrologic component of the model was run at an hourly time step and calibrated using streamflow data from two U.S. Geological Survey (USGS) streamflow-measurement stations for the period of October 1, 1994, through October 29, 1998. Daily precipitation data from one National Oceanic and Atmospheric Administration (NOAA) meteorologic station and hourly data from one NOAA meteorologic station were used for model input. The difference between observed and simulated streamflow volume ranged from -2.3 to 5.3 percent for a 10-month portion of the calibration period at the two calibration sites. Annual differences between observed and simulated streamflow generally were greater than the overall error for the 4-year period. For example, at Christina River at Coochs Bridge, near the bottom of the free-flowing part of the subbasin (drainage area of 21 mi2), annual differences between observed and simulated streamflow ranged from -6.9 to 6.5 percent and the overall error for the 4-year period was -1.1 percent. Calibration errors for 36 storm periods at the three calibration sites for total volume, low-flow-recession rate, 50-percent lowest flows, 10-percent highest flows, and storm peaks were within the recommended criteria of 20 percent or less. Much of the error in simulating storm events on an hourly time step can be attributed to uncertainty in the rainfall data.

The water-quality component of the model was calibrated using nonpoint-source monitoring data collected at two USGS streamflow-measurement stations and other water-quality monitoring data. The period of record for water-quality monitoring was variable at the stations, with a start date ranging from October 1994 to January 1998 and an end date of October 1998. Because of availability, monitoring data for suspended-solids concentrations were used as surrogates for suspended-sediment concentrations, although suspended-solids data may underestimate suspended sediment and affect apparent accuracy of the suspended-sediment simulation. Comparison of observed to simulated loads for up to six storms in 1998 at the two nonpoint-source monitoring sites (Little Mill Creek near Newport and Christina River at Coochs Bridge, Del.) indicate that simulation error is commonly as large as an order of magnitude for suspended sediment and nutrients. The simulation error tends to be smaller for dissolved nutrients than for particulate nutrients. Errors of 40 percent or less for monthly or annual values indicate a fair to good water-quality calibration according to recommended criteria; much larger errors are possible for individual events. Assessment of the water-quality calibration under stormflow conditions is limited by the relatively small amount of available water-quality data in the subbasin.

Users of the Christina River subbasin HSPF model and HSPF models for other subbasins in the Christina River Basin should be aware of model limitations and consider the following if the model is used for predictive purposes: streamflow-duration curves suggest the model simulates streamflow reasonably well when measured over a broad range of conditions and time although streamflow and the corresponding water quality for individual storm events may not be well simulated; streamflow-duration curves for the simulation period compare well with duration curves for the 58-year period ending in 2001 at Christina River at Coochs Bridge, Del., and include all but the extreme high-flow and low-flow events; and calibration for water quality was based on limited data, with the result of increasing uncertainty in the water-quality simulation.

January 8, 2004

WRI WRIR 03-4214. MONTANA.

Ground-water quality for two areas in the Fort Peck Indian Reservation, northeastern Montana, 1993-2000. By Joanna N. Thamke and Karen S. Midtlyng, 54 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, U.S. Geological Survey Water-Resources Investigations Report 03-4214, 54 p., 5 figs.

Studies conducted by the U.S. Geological Survey and the Fort Peck Tribes during 1979-96 determined that ground-water quality in two areas of the Fort Peck Indian Reservation had been adversely affected by some land-use activities. During the early and mid-1990s, saline-water contamination of near-surface Quaternary aquifers in more than 12 square miles in and near the East Poplar oil field was documented and high nitrate concentrations were documented in ground water in a large study area underlain by the Tertiary Flaxville Formation. This report describes additional ground-water-quality investigations for these two areas conducted subsequent to the previous studies.

In the East Poplar oil field study area, the quality of water in the Quaternary deposits is highly variable. Dissolved-solids concentrations increased as much as 29,500 milligrams per liter (mg/L) in ground water beneath a large area during a 9- to 10-year period because saline ground water probably moved into the Quaternary deposits within the area. Dissolved-solids concentrations decreased as much as 40,750 mg/L in ground water beneath a smaller area during a 10-year period because saline ground water in this area probably was diluted by fresh water from the area and because upgradient saline water sources were diminished or terminated. Dissolved-solids concentrations remained constant in areas unaffected by saline water.

In the Flaxville and underlying aquifers study area, data collected during 1997-99 indicated that seasonal and long-term changes in nitrate concentrations were minimal in 15 of the 16 wells sampled. Concentrations of pesticides in water from six sampled wells were less than the minimum reporting level.

January 8, 2004

OFR OFR 03-292. MONTANA, IDAHO, WASHINGTON.

Water-quality, streambed-sediment, and biological data from the Clark Fork-Pend Oreille and Spokane River Basins, Montana, Idaho, and Washington, 1998-2001. By Craig L. Bowers Rodney R. Caldwell DeAnn M. Dutton, 203 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, USGS Open-File Report 03-292, 203 p., 6 figs.

Water-quality, streambed-sediment, and biological data were collected in the Clark Fork-Pend Oreille and Spokane River basins as part of the U.S. Geological Survey's National Water-Quality Assessment Program and are presented in this report. These river basins compose the Northern Rockies Intermontane Basins study unit which was selected to include a river system that has a mixture of forested, agricultural, urban, and developing areas. Water-quality samples were collected from 28 surface-water sites and 86 ground-water sites from June 1998 to September 2001. Data collected included measurements of physical properties and chemical analyses of concentrations of major ions, trace elements, nutrients, organic carbon, pesticides, volatile organic compounds, and radiochemical constituents. Streambed-sediment and biological tissue samples were collected from 41 sites and analyzed for trace elements and organochlorine compounds. Benthic algae were collected to determine chlorophyll concentration and areal density.

January 8, 2004

WRI WRIR 03-4239. IDAHO, WASHINGTON.

Surface-water/ground-water interaction of the Spokane River and the Spokane Valley/Rathdrum Prairie Aquifer, Idaho and Washington. By Rodney R. Caldwell Craig L. Bowers, 60 pages.

Available from the U.S. Geological Survey Earth Science Information Center, Open-File Reports Section, Box 25286, MS 517, Denver Federal Center, Denver, CO 80225, U.S. Geological Survey Water-Resources Investigations Report 03-4239.

Historical mining in the Coeur d'Alene River Basin of northern Idaho has resulted in elevated concentrations of some trace metals (particularly cadmium, lead, and zinc) in water and sediment of Coeur d'Alene Lake and downstream in the Spokane River in Idaho and Washington. These elevated trace-metal concentrations in the Spokane River have raised concerns about potential contamination of ground water in the underlying Spokane Valley/Rathdrum Prairie aquifer, the primary source of drinking water for the city of Spokane and surrounding areas. A study conducted as part of the U.S. Geological Survey's National Water-Quality Assessment Program examined the interaction of the river and aquifer using hydrologic and chemical data along a losing reach of the Spokane River. The river and ground water were extensively monitored over a range of hydrologic conditions at a streamflow-gaging station and 25 monitoring wells situated from 40 to 3,500 feet from the river. River stage, ground-water levels, water temperature, and specific conductance were measured hourly to biweekly. Water samples were collected on nearly a monthly basis between 1999 and 2001 from the Spokane River and were collected up to nine times between June 2000 and August 2001 from the monitoring wells.

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