68 CONSERVATION OF GROUND WATER 



where it is reused for irrigation. 21 It has been proposed that 

 the sewage effluent from Los Angeles be used for artificial re- 

 charge along the coastal sand dunes south of Santa Monica to 

 offset overdraft and halt saline-water encroachment in the west 

 basin of the Los Angeles Coastal Plain. Consideration is being 

 given also to the possibility of reusing for irrigation the sewage 

 effluent which now goes into San Francisco Bay. 



Another attractive solution to problems of deficient water 

 supplies is the importation from regions of surplus. Such im- 

 portations may be expensive, especially when they involve 

 facilities to carry water a hundred miles or more, but many 

 communities have been well justified in the expense and are 

 fortunate to have had the vision to divert these surpluses to 

 their use while the water was still unappropriated. The hab- 

 itable places in the arid West are generally not self-sufficient in 

 precipitation and are thus dependent upon a sort of "import" 

 via streams from the more humid but less habitable moun- 

 tainous regions. Here we are concerned, however, with im- 

 ports from beyond the watershed in which the community is 

 situated. 



The larger metropolitan areas in California are all depend- 

 ent to some extent upon such imports. San Francisco and Oak- 

 land derive their water supplies from pipelines extending, 

 respectively, to reservoirs on the Tuolumne and Mokelumne 

 Rivers in the Sierra Nevada. The small ground-water reser- 

 voirs bordering San Francisco Bay have been pumped so 

 heavily that salt water has moved landward as much as 5 miles 

 in some areas. As affected wells have been abandoned, the 

 imported water has been substituted in many cases for domes- 

 tic supplies. 



Los Angeles has been the outstanding importer of water in 

 the West for many years. In 1913, when its population was less 

 than 200,000, the city spent 25 million dollars for the Owens 

 Valley aqueduct, and since Hoover Dam was constructed, it 

 has underwritten bonds for 200 million dollars for the Colo- 



21 Hutchins, Wells A., Sewage Irrigation as Practiced in the Western States, 

 U.S. Dept. Agr. Tech. Bull. 675, 1939, 59 pp. 



