Ground-water resources in the Corpus Christi area-Nueces, San Patricio, Refugio, and Aransas Counties (fig. 1)-were investigated as part of a broader study of land and water resources of the four-county area (Kier and others, 1974a and 1974b; Kier and White, in preparation). Although surface water, primarily from Lake Corpus Christi on the Nueces River near Mathis, is the principal fresh water supply for the City of Corpus Christi and numerous other communities in the region (table 1), ground water is also a significant resource in the area. More than 24 million gallons a day (mgd), or approximately one-third of the demand for fresh water in the early 1970s, was met by ground-water supplies (table 2). About 58 percent of the ground-water pumpage was for rural/domestic and livestock purposes; about 25 percent was for irrigation in Nueces and San Patricio Counties.

This report delineates the occurrence and availability of fresh to slightly saline ground water (dissolved solids less than 3,000 milligrams per liter) in the four-county area (fig. 1). Specifically included are (1) the distribution of sands containing fresh to slightly saline water; (2) the direction and rate of ground-water flow; (3) the content of total dissolved solids (TDS) in ground water, and the relation of the TDS to the direction and rate of ground-water flow; (4) the effects of ground-water withdrawal on water levels, quality of water, and flow direction; (5) estimates of the quantities of ground water available for future development, and delineation of the areas favorable for such development; and (6) potential problems limiting the availability and use of ground water in the Corpus Christi area.