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Open-File Report 01-335

Potentiometric Surface, Carbonate-Rock Province, Southern Nevada and Southeastern California, 1998-2000


INTRODUCTION

The potentiometric surface of water levels measured from 1998 to 2000 in the carbonate-rock province in southern Nevada and southeastern California is shown in plate 1, which was prepared in cooperation with the Nevada Division of Water Resources. The water-level contours displayed are similar to and modeled after work by Winograd and Thordarson (1975), Waddell and others (1984), Thomas and others (1986, 1996), and Laczniak and others (1996). The carbonate-rock province, as defined by Mifflin (1968), Hess and Mifflin (1978), and Harrill and others (1983), encompasses about 100,000 square miles of the eastern half of the Great Basin, and includes the eastern half of Nevada, much of western Utah, and part of southeastern Idaho (pl. 1). Plate 1 focuses on about 20,000 square miles of the carbonate-rock province in southern Nevada.

Purpose and Scope

The purpose of this report is to provide a current, generalized description of ground-water levels in consolidated rocks of the carbonate-rock province in southern Nevada. These ground-water levels are shown on plate 1 as contour lines that represent the regional potentiometric surface of ground water based on measurements made from 1998 to 2000. Also included in the report are 26 hydrographs that convey general water-level trends in the map area from 1985 to 2000. These hydrographs show water-level measurements in wells completed primarily in carbonate rock (fig. 1); water-level measurements in wells completed in basin-fill deposits (fig. 2); and discharge data from selected springs that issue primarily from carbonate rock (fig. 3). Hydrogeologic and physical data for these wells and springs are in table 1, table 2, and table 3.

Previous Investigations

Geologic investigations of the carbonate-rock province date from the late 1860's. Since then numerous studies have been completed describing geologic formations, metamorphic core complexes, and geologic structure. Investigations of southern Nevada ground water began in the early 1900's. Mendenhall (1909, p. 13) suggested that many of the desert springs in southern Nevada derive their flow from distant recharge areas rather than from nearby rainfall. U.S. Geological Survey (USGS) studies in the carbonate-rock province began in the 1960's, when a systematic reconnaissance was made of all unstudied basins in Nevada to assess potential ground-water resources. The USGS Regional Aquifer-System Analysis Program was started in 1978 following a congressional mandate to develop quantitative appraisals of the major ground-water systems of the United States. In 1981, the USGS began to evaluate the hydrogeology in the Basin and Range physiographic province for potential use for storage of high-level radioactive waste (Bedinger and others, 1989, 1990). In the early 1990's, the Nevada Carbonate Aquifer Program (in cooperation with the State of Nevada, Las Vegas Valley Water District, City of North Las Vegas, and the Bureau of Reclamation) was developed to monitor and collect hydrologic data from carbonate wells and springs throughout southern Nevada (Dettinger and others, 1995). An evaluation of the geochemistry in the carbonate-rock province was recently completed (Thomas and others, 1996) and water-level investigations and monitoring efforts are ongoing.


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