RECHARGE AND DISCHARGE AREAS FOR THE PRINCIPAL BASIN-FILL AQUIFER, BERYL-ENTERPRISE AREA, IRON, WASHINGTON, AND BEAVER COUNTIES, UTAH

The primary source of drinking and irrigation water in the Beryl-Enterprise area is ground water from the principal basin-fill aquifer. We mapped recharge and discharge areas for the principal aquifer to provide a tool for management of potential contaminant sources to help protect ground-water quality. Areas are delineated based primarily on the presence or absence of thick (> 20 feet) clay or silt confining layers and net ground-water gradient as determined from drillers' logs of water wells. Primary discharge areas lack thick confining layers, secondary recharge areas have thick confining layers and a downward vertical gradient, and discharge areas have thick confining layers and an upward vertical gradient. The Beryl-Enterprise area includes Escalante Valley and part of the Escalante Desert in southwestern Utah. The principal basin-fill aquifer of the Beryl-Enterprise area consists of interbedded alluvial-fan and lacustrine deposits. Water quality is generally moderately good with total-dissolved-solids values at or below 1000 mg/L recorded across much of the Beryl-Enterprise area, but most ground water is hard to very hard. Table Butte, the mountains surrounding the Beryl-Enterprise area basin floor, and the upper parts of alluvial fans along the margins of these uplands make up the primary recharge areas. The principal discharge area occupies the central and northeastern parts of the basin floor, based on water levels at the time the wells were drilled. Discharge exceeds recharge in the basin-fill aquifer, resulting in a declining water table throughout much of the Beryl-Enterprise area. Consequently, the discharge area is shrinking and should be treated as a secondary recharge area for land-use planning.