The U.S. Geological Survey, in support Data on groundwater quality are cornof the U.S. Department of Energy, Yucca pared to established, proposed, or tentative Mountain Site-Characterization Project, col-primary and secondary drinking-water stanlects, compiles, and summarizes hydrologic dards. Characteristics and constituents which data in the Yucca Mountain region. The data exceeded established, proposed, or tentative are collected to allow assessments of ground-drinking-water standards are listed for 18 water resources during studies to determine sites. Detected organic compounds forwtiich the potential suitability of Yucca Mountain established, proposed, or tentative drinkingfor storing high-level nuclear waste, water standards exist also are listed. Data on groundwater levels at 36 sites, groundwater discharge at 6 sites, groundwater quality at 19 sites, and groundwater INTRODUCTION withdrawals within Crater Flat, Jackass Flats, Mercury Valley, and the Amargosa Desert are Investigations are planned to determine the presented. Data on groundwater levels, potential suitability of Yucca Mountain for storing discharges, and withdrawals collected by high-level nuclear waste. The U.S. Department of other agencies (or as ?art of other programs) Energy (USDOE) has declared that all facilities are included to further indicate variations and activities associated with such investigations will be operated in a manner that maintains or through time at selected monitoring locations. protects environmental quality, and has Data are included in this report from 1910 established programs to allow assessments of through 1992. environmental quality. In April 1989, the U.S. A statistical summary of groundwater Geological Survey (USGS) began a cooperative levels at seven wells and median annual program with USDOE to develop a monitoring groundwater withdrawals in Jackass Flats is program for water resources in the vicinity of presented. The statistical summary includes Yucca Mountain. The purposes of the waterthe number of measurements, the maximum, resources monitoring program are to (1) document minimum, and median water-level altitudes, the historical and current condition of groundand the average deviation of water-level water resources, (2) detect and document changes altitudes for selected baseline periods and for in those resources during the investigations of calendar year 1992. Median annual ground-Yucca Mountain, and (3) provide a basis for water withdrawals in Jackass Flats are includ-analyzing and identifying potential adverse effects on water resources resulting from investigations ed also. of Yucca Mountain.