From October 1971 through October 1974. the U.S. Geological Survey collected ground-water data in the basins in Texas west of the Pecos River drainage area and northwest of the Big Bend country. The basins included are, from east to west: The Presidio Bolson; the Salt Basin; Green River Valley, Eagle Flat, and Red Light Draw. These data, which were collected in cooperation with the Texas Department of Water Resources (formerly Texas Water Development Board), will provide information for a continuing assessment of water availability within the State.