The San Bernardino Valley Municipal Water District began receiving its initial entitlement of 46,000 acre-feet (5.7 x 107 cubic metres) per year of imported northern California water in December 1972. By 1990, the district will be receiving 102,000 acre-feet (1.3 x 108 cubic metres) per year. Plans are to distribute this imported water for artificial recharge to the local ground-water system.
The upper Santa Ana River area is well suited for artificial recharge because it is largely underlain by permeable river-channel deposits. Some sandy clay, silt, and cemented sand and gravel layers occur that may locally retard downward percolation of recharge water. However, test drilling indicates none of these is extensive enough to impede recharge in the spreading grounds.
Analyses of ground-water movement during current water-spreading operations, test-drilling data, and application of Baumann's (1965) equation for calculating the theoretical size of the recharge mound indicate that
(1) barriers to ground-water movement are not evident in the river-channel deposits, (2) depth to the basement complex is less in the area of the eastern spreading basins than in the western basins, (3) the spreading grounds would be capable of accepting a combined total of as much as 80,000 acre-feet
(9.9 x 107 cubic metres) per year, and (4) the water being recharged should move through the part of the aquifer composed of river-channel deposits toward the areas of pumpage.
