70 CONSERVATION OF GROUND WATER 



ring water from areas of surplus to areas of water deficiency 

 is the Central Valley of California Project of the Bureau of 

 Reclamation. This project, originating as the state Water 

 Plan by the state engineer of California, includes transfer of 

 several million acre-feet annually from the Sacramento Valley 

 to the San Joaquin Valley. The "Central Arizona" plan for 

 importation from the Colorado River to overcome water de- 

 ficiencies in the Gila River Basin is of similar stupendous 

 proportions. The plan is being considered by Congress, but 

 many years can be expected to elapse before the delivery of the 

 first water, if the controversy between Arizona and California 

 as to Colorado River water rights must first be settled. In any 

 case, the diversion must await the regulation of the Colorado 

 River flow by dams not yet constructed above Hoover Dam. 



San Joaquin Valley, Calif.- 2 San Joaquin Valley (the 

 southern two-thirds of California's "Central Valley") is by 

 far the greatest user of ground water in the United States. 

 It is estimated that about 7 million acre-feet of water is 

 pumped annually from some 40,000 irrigation wells — 

 nearly a quarter of all the water that is produced by wells 

 throughout the nation. 



The long-term average stream flow into San Joaquin Val- 

 ley (from the Mokelumne River south) is of the order of 1 1 

 million acre-feet. With the aid of several reservoirs, most of 

 this surface water is utilized for irrigation by gravity diver- 

 sion, and the outflow through the San Joaquin River at the 



22 References: Trauger, F. D., "Description of an Early Experiment in 

 Ground-water Recharge through Wells at Lindsay, Cali- 

 fornia," Unpublished rept., 1949, 10 pp. 



Muckcl, D. C, "Report to Cooperators on Water-spreading 

 Investigations in San Joaquin Valley, California," U.S. Soil 

 Cons. Service rept., pp. 4—16, April 1949. 



"Comprehensive Plan for Water Resources Development, Cen- 

 tral Valley Basin, Calif.," U.S. Bur. Reel. Project Planning 

 Rept. 2-4, 0-3, p. 229, November 1945. 



Stoner, D. S., "Groundwater Investigations in the Central 

 Valley," U.S. Bur. Reel. Region 2, Mimeo. rept., July 1950, 

 172 pp. and 34 plates. 



