PROBLEMS FROM DEVELOPMENT 77 



by salvaging water now wasted by evaporation and transpira- 

 tion and by taking measures to reduce the salt inflow to the 

 basin water supply. 



RESERVOIRS WITH NATURAL REPLENISHMENT 

 ADEQUATE FOR PRESENT USES 



In many ground-water reservoirs of the arid regions the 

 average annual recharge is adequate for present uses. Indeed 

 the number of such reservoirs is far greater, and their total 

 areal extent is larger than the reservoirs in which current draft 

 from wells now exceeds the estimated average rate of replen- 

 ishment. 



The natural setting for all basins in the arid regions is 

 similar in that neither the seasonal nor annual precipitation 

 is sufficient to meet the requirements of agriculture, or of in- 

 dustry or communities because their requirements per unit of 

 area are ordinarily at least as great as those for farming. Com- 

 munities in these regions must depend upon the limited sur- 

 pluses of water from mountainous areas of more humid cli- 

 mate. It is inevitable that the density of population throughout 

 the West must continue to be less than in the humid East. The 

 regions where surface and ground-water supplies are still ade- 

 quate differ from the "overdeveloped" areas chiefly in the 

 degree of present development and use of water. They, too, 

 can reach a "critical" point at some stage of increased develop- 

 ment, because there just is not enough water to meet demands 

 comparable to those met in regions of abundant rainfall. 



The ground-water reservoirs here considered as having 

 adequate replenishment are by no means devoid of ground- 

 water problems. As the number of producing wells has in- 

 creased, there has inevitably been a lowering of water table 

 or artesian pressure in many areas, with resulting decline or 

 cessation of yield from flowing wells, and increased cost of 

 obtaining water by pumping. Some closely spaced wells have 

 interfered with each other, and the yield from each has 

 dropped off. Climatic cycles have caused concern in several 

 areas because the subnormal replenishment in a series of dry 



