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Show 44 WATER SUPPLY TO THE GREAT SALT LAKE The water supply in the Great Salt Lake Drainage Basin is a result of the climate and geology of the region. Because the Great Salt Lake Basin is closed, the only water supplies to the Basin are precipitation and imports from outside the Basin, as surface inflow or groundwater. Outflow from the Basin is either through evapotranspiration ( consumptive use) or exports. Because surface exports from the Basin are very small, virtually all of the precipitation that occurs in the Basin is either consumptively used, evaporated or stored in the Basin. Table 5 shows the water budget for the Great Salt Lake. TABLE 5 GREAT SALT LAKE WATER BUDGET ( 1,000 Acre- Feet Per Year) ( 1) ( 2) ( 3) ( 4) ( 5) ( 6) Surface Groundwater Precipitation Wetland Lake Lake Inflow Inflow on Lake Consumptive Use Evaporation Elevation 1,600 150 533 150 2,133 4,193 ( 1) Present modified inflow based on 1972 use and 1931- 1960 average water supply. ( 2) Estimated at 150,000 acre- feet. Other estimates vary from 75,000 acre- feet to 500,000 acre- feet. ( 3) Based on 10 inches annual precipitation and Lake surface area of 640,000 acres at elevation 4193. ( 4) Estimated consumptive use on managed wetland areas. ( 5) Based on 40 inches annual evaporation and Lake surface area of 640,000 acres at elevation 4193. Other estimates of evaporation vary from 36 inches to 50 inches. ( 6) Lake elevation with a surface area of 640,000 acres, which balances the water budget. |