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Proceedings of the U.S. Geological Survey (USGS) Sediment Workshop, February 4-7, 1997


C. Voigt, Washington, D.C.
T. Bozorth, Billings, MT
B. Carey, E. Janes, Lakewood, CO,
and S. Leonard, Prineville, OR

The Bureau Of Land Management (BLM) is responsible for managing 264 million acres of public land that are owned by the America people. Most of these lands are located in the Western United States. Use of the public lands has changed over time and will continue to change. One of the most challenging effects of both natural and use-related change is the generation, movement, and deposition of sediment. The BLM is quantifying, studying, and managing sedimentation. The three areas that are the cornerstones of BLM sediment-related efforts are riparian health, abandoned mine land restoration, and salinity control. It is important to note that the BLM addresses sedimentation issues by implementing management actions on the land; we are primarily interested in tangible results based on applying best management practices. The BLM does not, as a rule, allocate major funding support toward sediment research that is not directly applicable to on-the-ground applications.

Riparian Health

The BLM has established a National Riparian Service Team (NRST) that is currently focused on adapting and applying research findings rather than carrying out research. The team is heavily oriented toward training and consultation that emphasize evaluating natural functions of riparian areas and restoring proper functioning conditions using existing technologies. One component of properly functioning condition is that riparian areas and their associated water bodies are in balance with sediment and water supplied by the watershed (i.e., no excessive erosion or deposition). The team is currently focusing on relationships to and management of grazing practices; however, relationships to the entire watershed, including the impacts of roads, upland conditions, fire, flow regulation, and other factors, are also addressed.

Abandoned Mine Land Restoration

As part of a pilot Abandoned Mine Land Watershed Project, the BLM is working with the U.S. Forest Service (USFS), USGS and the State of Montana to measure the geochemistry of streams in a watershed affected by mining. Geologic mapping and evaluation of old ferricrete deposits will assist in determining the pre-mining background values for the ore metals in sediments. Examination of paleontological records in cores will attempt to determine if a viable fish habitat existed in these streams prior to mining.

This project is also looking at characterizing existing conditions. Watershed-scale variations are being evaluated by synoptic sampling of water, colloid, and bed sediment chemistry. Coupled with discharge, this will refine the characterization of metal concentrations by adding colloid information.

Salinity Control

Weathering, runoff, and the sedimentation process on the extensive salt-laden marine deposits of the Colorado Plateau all contribute to the salt loading of the Colorado River. Numerous large point sources are also part of the salt discharge through the system. The Colorado River is unique. Although it heads among snow-covered peaks, it soon descends rapidly from the mountains into increasingly arid, and often saline landscapes, and river salinity increases in a downstream direction. However, most other western rivers flow into more mesic regions, and salinity decreases in the downstream direction. BLM's first efforts to reduce salt loading began on two fronts: (1) cooperative studies and research and (2) efforts to locate and control flowing saline wells and springs. However, since the passage of the Water Quality Act of 1987, emphasis has gradually shifted to reducing salt loading through improved land management and erosion controls in hopes of preventing or delaying the delivery of salts in solution and saline sediments to the Colorado River's tributary system. The BLM is just one participant in the federal salinity control initiative, along with the Natural Resources Conservation Service (NRCS), the Bureau of Reclamation (BOR) and water agencies of the seven Basin States.

Suggested Research Areas of Interest

  1. Natural resource damage claims regarding mining impacts to public lands are usually based on toxic-metal-laden sediments and their impacts to degrading public land resources. Understanding metal precipitation in relation to pH is an area that would benefit from research in watershed conditions.

  2. The practical significance of the colloid fraction is its toxicity to aquatic life and related issues of beneficial uses and water-quality standards. Colloids may be more toxic than either truly dissolved or larger particulate phases. Any serious attempt at water-quality restoration to support aquatic life must consider the formation, transport, and fate of the colloid fraction.

  3. There is a very urgent need between State and Federal agencies for methodologies to address sediment impacts and the sediment-TMDL problem. How does one evaluate a stream reach to determine the magnitude of adverse impacts to designated beneficial uses due to sediment? This question applies mostly, but not exclusively, to aquatic life beneficial use categories. How does one incorporate nonpoint sources in general and sediment in particular into the TMDL process?

  4. In the Mancos-shale landscape, most long-term studies have shown that sediment transport is closely linked to salt release, and thus to salt loading. Since the highest sediment-producing streams (e.g., the Dirty Devil in Utah) yield the greatest salt tonnages, additional USGS research on upland erosion and sedimentation processes in such Upper Basin tributaries would improve BLM's understanding and management of these large salt producers. There is also a need for improving our understanding of the seasonal changes at the surface crust of Mancos-shale derived soils in priority areas of Colorado, Utah, and Wyoming. Seasonal soil surface changes exert a significant influence on the runoff, sediment yield, and salt loading behavior of these lands. During the change in seasons, freeze-thaw effects, raindrop compaction, and human and livestock use all combine to modify the water-handling properties of the soils. Depending on timing, heavy rainfall or snowmelt flooding can produce quite different hydrologic effects.

  5. Hillslope inclination in relation to the electrical conductivity of hillslope plot solute yields could be used to estimate the salt load of a small ungaged basin underlain by marine shales. This could be very helpful for analyzing salt yield and potential watershed treatments from small rangeland drainages.

  6. The patchwork complexity of public lands in and adjacent to other uses and jurisdictions presents challenges to the watershed analyst. For example, how should nutrient or sediment loads be allocated to portions of a watershed that are in different ownerships? Varying land uses/land management practices can also overlay the land ownership pattern, further confounding the allocation of pollutant loading.
Workshop Proceedings
Contributions from Other Federal Agencies
Contribution from the USGS