96 CONSERVATION OF GROUND WATER 



as a supplement to low precipitation and stream flow. As 

 with surface reservoirs, full use of a ground-water reservoir 

 cannot be achieved by attempting to hold the storage at a 

 constant level. Maximum use is achieved if some of the 

 inflow of wet years is held in storage until dry years when 

 there is greatest need for it. The use of ground-water reser- 

 voirs for holdover storage is well established in some valleys 

 in southern California. San Fernando Valley in particular, be- 

 cause of the availability of surplus water from Owens Valley 

 in some seasons, has been used for holdover storage of ground 

 water. 



San Fernando Valley, Calif. 26 The San Fernando Valley 

 ground-water reservoir is the property of the city of Los 

 Angeles by the terms of an ancient Spanish grant, and pump- 

 age by towns such as Glendale and Burbank or by private 

 individuals is through the courtesy of that city. Los Angeles, 

 too, has used that reservoir for water supply but in wet years 

 uses it chiefly to store surplus water from the Owens Valley 

 aqueduct and floodwaters from several flood-control proj- 

 ects. In those years, the recharge may exceed the discharge 

 by several thousand acre-feet, as shown in the following 

 table. The total capacity of the ground-water reservoir is un- 

 known, but computations by the California Division of 

 Water Resources indicate that more than 800,000 acre-feet 

 can be stored in a zone 100 feet thick (extending above and 

 below the water table of January 1933). 



Estimated Input and Outflow of San Fernando Ground-water Basin, 1943 



Input Acre-feet 



Recharge from rainfall penetration 73,000 



Irrigation and domestic return water (imported from Owens Valley) 34,000 



Water spreading and channel percolation 69,500 



Total input 176,500 



86 References: Geology and Ground-water Storage Capacity of Valley Fill, 

 South Coastal Basin Investigations, Calif. Div. Water Res. 

 Bull. 45, 1934, 273 pp. 

 Blaney, H. F., and W. W. Donnan, "Ground-water Situation 

 in San Fernando Valley, California," U.S. Soil Cons. Service, 

 Mimeo. rept., December 1945, 56 pp. 



