Selected ground-water data for Yucca Mountain region, southern Nevada and eastern California, through December 1996

The US Geological Survey, in support of the US Department of Energy, Yucca Mountain Site Characterization Project, collects, compiles, and summarizes hydrologic data in the Yucca Mountain region. The data are collected to allow assessments of ground-water resources during studies to determine the potential suitability of Yucca Mountain for storing high-level nuclear waste. Data on ground-water levels at 36 sites, ground-water discharge at 6 sites, and ground-water withdrawals within Crater Flat, Jackass Flats, Mercury Valley, and the Amargosa Desert are presented for calendar year 1996. Data collected prior to 1996 are graphically presented and data collected by other agencies (or as part of other programs) are included to further indicate variations of ground-water levels, discharges, and withdrawals through time. A statistical summary of ground-water levels at seven wells in Jackass Flats is presented to indicate potential effects of ground-water withdrawals in support of US Department of Energy activities near Yucca Mountain. The statistical summary includes the number of measurements, the maximum, minimum, and median water-level altitudes, and the average deviation of measured water-level altitudes for selected baseline periods and for calendar years 1992--96. At two water-supply wells and a nearby observation well, median water levels for calendar year 1996 were slightly lower (0.3 to 0.4 foot) than for the respective baseline periods. At four other wells in Jackass Flats, median water levels for 1996 were unchanged, slightly lower (0.2 foot), and slightly higher (0.2 and 0.7 foot) than for the respective baseline periods