52 CONSERVATION OF GROUND WATER 



occupied by fresh water has been reported along the shores 

 of San Francisco Bay and in the lower part of the adjacent 

 Santa Clara Valley; in the lower end of Salinas Valley; along 

 the Los Angeles Coastal Plain from Venice to Newport Beach; 

 and near Ventura, San Juan Capistrano, Oceanside, and San 

 Diego. The coastal Goleta Valley near Santa Barbara is also 

 pumping ground water below sea level but is protected from 

 salt-water encroachment by a fault barrier. 



Santa Clara Valley, Calif. 11 The Santa Clara Valley em- 

 braces nearly 200,000 acres, of which 121,000 are irrigated 

 lands and municipal areas within the Santa Clara Valley 

 Water Conservation District. Practically all the water for 

 irrigation, municipal, and industrial use is pumped from 

 wells. In recent years more than 2,000 wells have pumped 

 an estimated 210,000 acre-feet a year, which is believed to 

 be about 35,000 acre-feet more than the average annual re- 

 plenishment. In much of the valley area the ground-water 

 reservoir is confined beneath a clay blanket and not suscep- 

 tible to appreciable replenishment by downward percola- 

 tion from the surface. The recharge areas for the ground- 

 water reservoir consist of narrow, discontinuous belts of 

 gravel and sand along the borders of the valley, and espe- 

 cially the permeable areas along the channel of Coyote River 

 and its tributaries. 



Pumping from wells for irrigation began in 1908 but until 

 1917 was generally less than the average annual replenish- 

 ment. By 1918, the annual draft had climbed above 50,000 



n References: Hunt, G. W., Description and Results of Operation of the 

 Santa Clara Water Conservation District's Projects, Trans. 

 Am. Geophys. Union, vol. 21, part I, pp. 13-22, 1940. 

 Tolman, C. F., and J. F. Poland, Ground Water, Salt-water 

 Infiltration and Ground-surface Recession in Santa Clara 

 Valley, Calif., Trans. Am. Geopliys. Union, vol. 21, pp. 7, 

 23-34, 1940. 

 Hunt, G. W., "Proposed Lexington Dam and Conservation 

 Works," Report to Board of Directors of Santa Clara Valley 

 Conservation District, 1947, 29 pp. 



