The U.S. Geological Survey, in cooperation with the U.S. Air Force, Holloman Air Force Base, studied the potential change in water levels that could occur as a result of increased groundwater withdrawals from the middle-Tertiary to Holocene age basin-fill and alluvial deposits in the vicinity of the Air Force base in Otero County, New Mexico. Water level changes of 25 ft to as much as 60 ft below their 1982 levels are projected in the well field areas by the year 2001, based on an increased groundwater withdrawal of 10%. The 400-sq-mi area of unconsolidated material is relatively flat except for the alluvial fans adjacent to the mountain front. Perennial streams are not present in the study area. The aquifer has a saturated thickness that ranges from 0 to 3 ft. Intermittent streamflow from the nearby mountains infiltrates the alluvial fans and recharges the aquifer system. Groundwater is discharged from the area by underflow, evapotranspiration, and pumpage withdrawals from wells. (USGS)