The Tule Valley drainage basin is an area of about 940 square miles in Juab and Millard Counties in west-central Utah. Precipitation in the basin averages about 8 inches annually. There is no surface outflow and all streams are ephemeral. Annual runoff averages about 0.09 inch. Because there is no sustained runoff, and flow is local and infrequent, reservoirs do not provide dependable water supplies. Ground-water recharge from precipitation in the basin is estimated to average 7,600 acre-feet annually. Discharge, principally by evapotranspiration, averages about 40,000 acre-feet annually. Subsurface inflow from adjacent areas is estimated to average about 32,000 acre-feet annually.