Proceedings of the U.S. Geological Survey (USGS) Sediment Workshop,
February 4-7, 1997
SEDIMENT RELATED ISSUES AND THE PUBLIC
LANDS-EXPANDING SEDIMENT RESEARCH
CAPABILITIES IN TODAY'S USGS-A BUREAU OF LAND
MANAGEMENT OVERVIEW
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
- 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.
- 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.
- 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?
- 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.
- 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.
- 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