Abstract

The total average precipitation falling in the Uinta Basin is estimated to be 8 million acre-feet per year and the total transbasin inflow is estimated to be 3.6 million acre-feet. About 6.7 million acre-feet per year of water is consumed primarily by evaporation of precipitation, surface water, and soil moisture, and by transpiration from vegetation (other than phreatophytes and crops); 243,000 acre-feet per year by evapotranspiration from the ground-water reservoirs; 460,000 acre-feet per year is consumed by crops (surface-water supplies); and 12,000 acre-feet per year directly from wells and springs (some of which is used for irrigation). The total transbasin outflow from the area is about 4.2 million acre-feet per year.

Ground water occurs in unconsolidated valley fill and consolidated rocks. Recharge to groundwater reservoirs from precipitation, infiltration of irrigation water, and return flow from well discharge (includes some return flow from springs) is estimated to be 630,000 acre-feet per year. The estimated recoverable ground water in storage in the northern Uinta Basin is 28 million acre-feet and in the southern Uinta Basin it is 3.19 million acre-feet. Discharge from the ground-water reservoirs by springs, leakage to streams, evapotranspiration, and withdrawal from wells is estimated to be 630,000 acre-feet per year.

The dissolved-solids concentrations of ground water varies from less than 1,000 to more than 35,000 milligrams per liter. Ground water in both unconsolidated valley fill and consolidated rocks generally is fresh in the higher altitudes of the basin, and ground water in the central part of the basin varies from fresh to briny.

Increased ground-water withdrawals from unconsolidated valley fill will decrease streamflow. Increased ground-water withdrawals from consolidated rocks in the higher altitudes of the basin may decrease discharge from springs or base flow of streams. Withdrawals from consolidated rocks in the central part of the basin will cause large water-level declines.