PROBLEMS FROM DEVELOPMENT 83 



are the principal sources of municipal and irrigation water 

 used in the valley. There are also about 1,100 wells in the 

 lower part of the valley, most of them flowing and some 

 large enough to be used for irrigation. The wells yield about 

 7,000 acre-feet a year, and an additional 10,000 acre-feet is 

 piped from springs to the American Smelting and Refining 

 Company's smelter at Garfield, for industrial use. Smaller 

 springs along the margins of the valley discharge about 

 5,000 acre-feet a year, most of which is not used. In addition, 

 ground water is discharged by evapotranspiration in an 

 extensive area in the northern part of the valley where it 

 borders Great Salt Lake. 



The average annual replenishment to the ground-water 

 reservoir is estimated to be more than twice the amount 

 currently put to beneficial use. Recharge is principally from 

 water in canyons draining the mountain ranges, with a small 

 contribution from precipitation within the valley. The re- 

 charge has been increased, at least temporarily, by water 

 flowing from the Elton tunnel, completed in 1941 into the 

 Bingham mining district, and has resulted in some increase 

 in flow from wells in the small Erda irrigation district. The 

 quantity of replenishment correlates closely with regional 

 precipitation, and since the drought of 1931 to 1935 there 

 have been appreciable increases of storage in the ground- 

 water reservoir. 



It has been estimated on the basis of detailed studies in a 

 few of these valleys and reconnaissance in several others that 

 water-loving vegetation in the arid regions may waste as much 

 as 25 million acre-feet of ground water, which is almost twice 

 the average annual flow of the Colorado River into Lake 

 Mead. 27 In the Great Basin, which includes nearly all Nevada 

 and extends into Utah, Idaho, Oregon, and California, not a 

 drop of water can flow to the oceans, and all precipitation ulti- 

 mately returns to the atmosphere; in this basin more than a 



27 Robinson, T. W., "Determination of Consumptive Use of Water by Native 

 Vegetation," Nevada State Engineer's Third Water Conference, 1949. 



