Digital-model evaluation of the ground-water resources in Ocotillo-Coyote Wells Basin, Imperial County, California

A flow model using finite-element techniques has been constructed for an alluvial aquifer in the Ocotillo-Coyote Wells Basin, Imperial County, Calif. Natural recharge is about 2,600 acre-feet per year, and estimated ground water in storage is 640 ,000 acre-feet. Pumpage totaled 880 acre-feet in 1975. The computed decline from steady-state conditions in 1925 to December 1975 was 15 feet in Ocotillo. The projected decline from 1976 to 1995 with annual pumpage of 1,000 acre-feet is 6 feet and with annual pumpage of 2,000 acre-feet is 17 feet in Ocotillo. In the latter projection, continued pumping after 1995 may cause saline water to flow toward the potable ground water in and around Ocotillo. (Woodard-USGS)