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Characterizing a Safe Repository for Nuclear Waste

he USGS historically has been active

in acquiring and analyzing hydrologic, hydrogeologic, and geologic information in southern Nevada as a part of ongoing local, State, and national programs. Following enactment of the Nuclear Waste Policy Act of 1982, the USGS expanded the investigations at and around Yucca Mountain, Nev., in cooperation with the Department of Energy (DOE). Yucca Mountain is currently the sole site being characterized as a potential site for a mined geologic repository for the long-term storage of high-level radioactive waste. Characterization of the mountain is necessary to determine its suitability as a location for a safe, permanent, underground repository. Site suitability will be determined by matching documented characteristics against Federal standards and regulations promulgated by the Nuclear Regulatory Commission, which ultimately will administer the licensing process.

Studies at Yucca Mountain are taking place in two physical settings. Surfacebased testing consists of detailed surface mapping, digging trenches to expose surficial geology, and drilling both deep and shallow boreholes for geophysical and (or) stratigraphic analyses and hydrologic testing of the unsaturated and saturated zones. Exploratory Studies Facility (ESF) testing will be done in a U-shaped tunnel about 5 miles long that enters the northern part of Yucca Mountain in a westerly direction, then will turn in a southerly direction in line with the crest of the mountain about 800 feet beneath the crest, and ultimately will turn in an easterly direction to exit the mountain. The ESF, construction of which began in April 1993, will provide underground access to geologic and hydrogeologic features for refining results of surface-based testing. In addition to extensive hydrologic and seismic monitoring, representative accomplishments in FY 1993 include: • Completed maps that establish the abundance, distribution, and geographic orientation of known and suspected Quaternary faults within about 62 miles of Yucca Mountain. • Completed draft reports for the resolution of issues centering around erosion

and the origin (atmospheric water or upwelling ground water) of calcite-silica deposits near faults. These reports should allow DOE to complete work on erosion and the calcite-silica issues. • Dry drilling and coring of the first deep, unsaturated-zone hydrologic test hole, which reached a depth of about 1,670 feet. Core and stratigraphic analyses have begun. • Successful installation of sensitive seismographs in two boreholes in excess of 1,640 feet deep to provide documentation of microearthquakes that could not otherwise have been accurately recorded. • Continued mapping of the lateral extent of the Ghost Dance fault at a scale of 1:240 (1 inch=20 feet) in order to resolve any potential effects on the design of the repository, such as fast pathways for water within the unsaturated zone.

G. Louis Ducret

serves as senior manager for the Yucca Mountain Project Branch

For more information on the Yucca Mountain project, contact:

Telephone (303) 236–0516 Internet gaucret(a

Cooperative FederalState Water Resources Activities he Federal-State Cooperative Water Resources program is a unique partnership between the USGS and State and local agencies. Although State and local cooperators provide at least half the funds, the USGS conducts most of the work. For almost 100 years, studies under this program have contributed to the advancement of earth science and the compilation of a major part of the Nation's hydrologic information. From its earliest days, the responsibility for developing stream-gaging procedures, concepts of surface- and ground-water flow, and analytical techniques for investigations of water quality has been vested in the program. In 1993, hydrologic-data collection, interpretive investigations, and research were conducted as part of the cooperative program by USGS scientists located in offices in every State, Puerto Rico, and several territories, through agreements with more than 1,000 cooperating agencies. The number of investigations that emphasize water-quality issues, such as aquifer contamination, river-water quality, stormwater-runoff quality, and the

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effects of acid rain, coal mining, and agricultural chemicals and practices on the hydrologic system, has increased since the early 1970's. The following are examples of investigations into water quality and other related topics conducted as part of the cooperative program.

Florida: Ground water and wetland interaction.—The Everglades ecosystem thrives in water having very low phosphorus concentrations. Recent urban and agricultural development in the surrounding areas have raised phosphorus concentrations enough to cause concern. As a result, the South Florida Water Management District has asked the USGS to investigate the ground water/surface water interactions in the Everglades. Once an improved understanding of the flow system has been developed, the sources, movement, and distribution of phosphorus will be analyzed with the objective of comparing different management techniques.

Kansas: Movement of pesticides in surface and ground water.—A cooperative project between the USGS, the Kansas State Board of Agriculture, and Kansas State University is determining the potential for decreasing the amount of atrazine and other triazine herbicides transported to surface and ground water. Concentrations of atrazine, alachlor, and their selected metabolites are being measured in suspended sediment in surface runoff under different land-management practices, such as terraced, clean-tilled, and ridge-tilled cornfields with and without grassed filter strips. The effects of these different land-management practices on the quality of ground water as well as on the volume of herbicides infiltrating to ground water are being evaluated.

Michigan and Wisconsin: Quality of water in streams tributary to Lake Superior.—The USGS, in cooperation with the Michigan and Wisconsin Departments of Natural Resources, is using state-ofthe-art technology to estimate the amount of contaminants reaching Lake Superior in inflow from its major tributaries. Data are being collected uniformly from throughout the Lake Superior region. A computerized long-term data base, now accessible to every agency studying the Great Lakes, provides information that is being used to evaluate efforts by State and Federal agencies to lessen the harmful effects of selected contaminants in Lake Superior.

Oregon: Water quality in the Tualatin River.—Excessive phosphorus in the Tualatin River has resulted in nuisance growths of planktonic algae and periodically low concentrations of dissolved oxygen in the lower part of the river. Although it has long been believed that water-quality problems could be solved by eliminating phosphorus from wastewater treatment plants and surface runoff from urban and agricultural lands, this USGS investigation in cooperation with the Unified Sewerage Agency of Washington County has shown that ground water discharging to the river and its tributaries contains phosphorus concentrations from 5 to 100 times larger than expected; these excessive concentrations are hampering clean-up efforts. Phosphorus in ground water comes from both human activities and natural sources, but some of the highest concentrations seem to occur naturally in an aquifer that contains large amounts of organic matter buried by catastrophic floods during the Pleistocene Epoch. Remediation strategies for the Tualatin River are being reviewed on the basis of results of the investigations to date, so that millions of dollars will not be spent on possibly ineffective “best management practices" in urban and agricultural areas.

South Carolina: Degradation rates of petroleum hydrocarbons.—The USGS, in cooperation with the South Carolina Water Resources Commission, is investigating an extensively contaminated, shallow water-table aquifer that underlies a fuel tank farm in Hanahan, S.C. Data collected to date reveal that petroleum hydrocarbons in the aquifer are being degraded anaerobically in a complex pattern of zones dominated by ironreducing, sulfate-reducing, and methanogenic (gas-producing) conditions that change dynamically over time and space. Further investigation is designed to determine relative rates of hydrocarbon degradation under these same aquifer conditions and how degradation rates are affected by continually changing conditions. The results will help responsible agencies design bioremediation strategies at this site and similar sites nationwide.

Bruce K. Gilbert has prepared annual reports describing the Federal-State Cooperative program and its accomplishments since 1983


The Truckee-Carson Program

fter decades of litigation and negoti

ation, the Truckee-Carson-Pyramid Lake Water Rights Settlement Act, Public Law (P.L.) 101–618, was passed in 1990. The law provides a framework for constructing a complex combination of operating criteria to balance interstate allocation of water and water demands for municipal, irrigation, fish and wildlife, water-quality, and recreational uses in the Truckee and Carson River basins of Nevada and California.

The USGS Truckee-Carson program was established to support the Department of the Interior in the implementation of P.L. 101–618 as follows: • Consolidate and (or) develop as necessary a streamflow and water-quality gaging-station network in order to document water resources and support river operations. • Calibrate, test, and use interbasin hydrologic and hydraulic computer models to support the management and allocation of water and the assessment of environmental effects. • Provide technical guidance to other Federal agencies during negotiations for the Truckee River Operating Agreement.

Computer models of the watersheds and geographic information system coverages are being linked with operation/allocations models (developed as a joint effort with the Bureau of Reclamation) so that alternative management scenarios can be analyzed at hourly, daily, weekly, seasonal, or annual time scales. Easy-toevaluate numerical, statistical, and graphical results allow managers to test and improve long-term operating policies responsive to the many competing demands for water. Although development and calibration of the models are basin specific, the underlying decisionsupport modeling system has national transfer value.

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The data network and the models adapted or developed by the USGS under the Truckee-Carson program will be used extensively by the Bureau of Reclamation, the Bureau of Indian Affairs, and the Fish and Wildlife Service. Principal State agencies benefiting from the program include the California Department of Water Resources, the California Department of Fish and Game, the Nevada Department of Conservation and Natural Resources' Divisions of Water Resources, Water Planning, and Environmental Protection, and the Nevada Department of Wildlife. Potential users include two Native American tribes, about a dozen counties in California and Nevada, and several utility and irrigation districts.

Larry R. Bohman has studied surface-water modeling for the USGS for the past 15 years

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National Research Program

he National Research Program (NRP), estab

lished in the late 1950's, encompasses a broad spectrum of scientific investigations. The program is designed to encourage research that provides new knowledge and insights into varied and complex hydrologic phenomena, processes, and systems that are neither well understood nor defined. The sciences of hydrology, mathematics, chemistry, physics, ecology, biology, geology, and engineering are used to gain a fundamental understanding of the processes that affect the availability, movement, and quality of the Nation's water resources. Results of the investigations conducted under the NRP are applicable not only to the solution of current water problems but also to future issues, anticipated or unanticipated, that may affect the Nation's water resources.

The emphasis of research activities has changed through time to reflect the emergence of promising new areas of inquiry and the demand for new tools and techniques with which to address water resources issues and problems. Many issues addressed by NRP scientists involve potential threats to human health, ecosystems, and (or) the potential high social costs of control or mitigation. Knowledge

gained and methods developed in this program apply to all of the hydrologic investigations of the USGS, to water-oriented investigations and operations of other agencies, and to the general scientific community.

In recent years, NRP scientists have: • Completed the Nation's first systematic waterquality study of the Mississippi River system. • Conducted a multidisciplinary study to develop the techniques and understanding needed to characterize fluid movement and chemical transport in fractured bedrock. • Discovered microorganisms that can naturally remove a variety of contaminants from ground water, including aromatic hydrocarbons and uranium. • Developed a method to identify recently recharged ground water, thereby helping to determine the vulnerability of ground water to contamination. • Developed a method for assessing the sensitivity of surface waters to acid deposition.

Linda C. Friedman is the assistant to the Chief of the Office of Hydrologic Research

For more information on National Research Program, contact:

Telephone (703) 648–5051 Internet

Acid Rain

trong acids (sulfuric and nitric acids),

formed when atmospheric pollutants emitted from powerplants, factories, and motor vehicles combine with water in the atmosphere, have fallen as acid rain and snow on the Northeastern United States and southeastern Canada during the last several decades. This acidic precipitation is believed to be responsible for the acidification of sensitive lakes and streams, damage to high-elevation forests and historical structures, and impaired visibility in affected areas. The USGS, in cooperation with other Federal agencies and many State agencies, is participating in a coordinated nationwide program to define the causes and effects of acid rain and to assess the benefit of reduced emissions of the precursors of acid rain, as required by the Clean Air Act Amendments of 1990. The USGS is the lead agency for monitoring deposition under the Federal Interagency National Acid Precipitation Assessment program (NAPAP).

Significant Downward Trend in Sulfate

peration of the National Trends

Network (NTN), a 150-station, nationwide, multiagency network for monitoring precipitation chemistry in the United States, is coordinated by the USGS. Selected sensitive lakes and streams throughout the Nation are monitored through the NTN to document changes in water chemistry that may result from the effects of acid rain, and research is conducted in several sensitive watersheds to define how the geochemical processes caused by acid rain affect water quality.

An analysis of trends was conducted in FY 1993 on data from the 33 stations in the NTN that had the longest records. The analysis covered 1980 through 1991 and showed substantial and statistically significant downward trends in sulfate deposition at 26 of the 33 stations. Downward trends in nitrate deposition were also preponderant but were statistically significant at only three stations. Trends

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