The Edwards aquifer is the sole source of public water supply for more than 1 million people in the San Antonio area and supplies large quantities of water for agriculture, industry, and the military. The dissolutioned, faulted limestone aquifer is the major source of water for Bexar, Comal, Hays, Medina, and Uvalde Counties. The annual compilation of estimates of ground-water recharge to and discharge from the Edwards aquifer is part of a continuing program of the U.S. Geological Survey (USGS) in cooperation wilh the Edwards Underground Water District (EUWD).