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U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2007–5261

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Foreword

Water demands from the lower Colorado River system are increasing with the rapidly growing population of the southwestern United States. To decrease dependence on this over allocated surface-water resource and to help provide for the projected increase in population and associated water supply in the Las Vegas area, water purveyors in southern Nevada have proposed to utilize the ground-water resources of rural basins in eastern and central Nevada. Municipal, land management, and regulatory agencies have expressed concerns about potential impacts from increased ground-water pumping on local and regional water quantity and quality, with particular concern on water-rights issues and on the future availability of water to support springflow and native vegetation. Before concerns on potential impacts to pumping can be addressed, municipal and regulatory agencies have recognized the need for additional information and improved understanding of geologic features and hydrologic processes that control the rate and direction of ground-water flow in eastern and central Nevada.

In response to concerns about water availability and limited hydrogeologic information, Federal legislation (Section 301(e) of the Lincoln County Conservation, Recreation, and Development Act of 2004: PL 108-424) was enacted in December 2004 that directs the Secretary of the Interior, through the U.S. Geological Survey (USGS), the Desert Research Institute (DRI), and a designee from the State of Utah, to conduct a water-resources study of the basin-fill and carbonate-rock aquifers in White Pine County, Nevada, and smaller areas of adjacent counties in Nevada and Utah. The primary objectives of the Basin and Range carbonate-rock aquifer system (BARCAS) study are to evaluate: (1) the extent, thickness, and hydrologic properties of aquifers, (2) the volume and quality of water stored in aquifers, (3) subsurface geologic structures controlling ground-water flow, (4) ground-water flow directions and gradients, and (5) distributions and rates of recharge and ground-water discharge. Geologic, hydrologic, and geochemical information are integrated to determine basin and regional ground-water budgets.

Results of the study are summarized in a USGS Scientific Investigations Report (SIR), prepared in collaboration with DRI and the State of Utah, and in cooperation with the Bureau of Land Management. The report was submitted to Congress in December 2007. The BARCAS study SIR is supported by USGS and DRI reports that document, in greater detail than the summary SIR, important components of the BARCAS study. These reports are varied in scope and include documentation of basic data including spring location and irrigated acreage, and interpretive studies of ground-water flow, recharge, evapotranspiration, and geology.

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