54 CONSERVATION OF GROUND WATER 



heavy precipitation produced runoff far in excess of the 

 capacities of combined natural and artificial percolating 

 systems. 



Thanks partly to a series of years of above normal rain- 

 fall and runoff, water levels in the valley rose more than 

 70 feet in the first 8 years of the District's operations. The 

 combination of increased pumping draft and deficient rain- 

 fall since 1943 has reversed the trend, however. By 1949 the 

 average water levels were only 15 feet higher than at the 

 time of the record minimum of 1934, and the pumping 

 lift exceeded 400 feet in some wells. At present, the District 

 is enlarging the facilities for storage and recharge of flood- 

 water and thus will minimize the waste to the bay during 

 years of abundant rainfall and runoff. As another possible 

 source of additional water, studies are being made of the 

 possibility of reclaiming the sewage effluent from the cities 

 in the San Francisco-Oakland-San Jose metropolitan area. 

 At present, this effluent amounts to about 250,000 acre-feet 

 a year and is discharged into San Francisco Bay, contribut- 

 ing to the low-tide fragrance of the eastern approaches to the 

 bay bridge. 



Salinas Valley, Calif. 12 The Salinas Valley floor covers 

 about 239,000 acres, of which 177,000 is classed as irrigable. 



7 7 7 £} 



In 1945, 127,000 acres of this land was irrigated, almost en- 

 tirely from wells. The total annual pumpage from wells in 

 recent years has been of the order of 370,000 acre-feet, which 

 is about 30,000 acre-feet more than the average annual re- 

 plenishment. On the other hand, 530,000 acre-feet flows out 

 from the valley to the Pacific Ocean in an average year, of 

 which about 90 per cent is the winter flow of the Salinas 

 River. 



There are significant differences in opportunities for nat- 

 ural replenishment in different parts of Salinas Valley. 

 Pumpage from the upper half of the valley has been of the 



12 Reference: Simpson, T. R., Salinas Basin Investigations, Calif. Div. Water 

 Res. Bull. 52, 1946, 230 pp. 



