The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, Office of Civilian Radioactive Waste Management, collected, compiled, and summarized hydrologic data in the Yucca Mountain region of southern Nevada and eastern California. These data were collected to allow assessments of ground-water resources during activities to determine the potential suitability or development of Yucca Mountain for storing high-level nuclear waste. Data collected from January through December 2005 are provided for ground-water levels at 35 boreholes and 1 fissure (Devils Hole), ground-water discharge at 5 springs, ground-water levels and discharge at 1 flowing borehole, and total reported ground-water withdrawals within Crater Flat, Jackass Flats, Mercury Valley, and the Amargosa Desert. Ground-water level, discharge, and withdrawal data collected by other agencies, or as part of other programs, are provided. A statistical summary of ground-water levels at seven boreholes in Jackass Flats is presented for 1992-2005 to indicate potential effects of ground-water withdrawals associated with U.S. Department of Energy activities near Yucca Mountain. The statistical summary includes the annual number of measurements; maximum, minimum, and median water-level altitudes; and average deviation of measured water-level altitudes compared to the 1992-93 baseline period. At seven boreholes in Jackass Flats, median water levels for 2005 were slightly higher (0.4-2.7 feet) than the median water levels for 1992-93.