PROBLEMS FROM DEVELOPMENT 95 



pumpage has been considerably greater than the rate of 

 replenishment and that water is being mined. The quantity 

 of water in the ground-water reservoir is so large that 

 pumping could continue at present rates for several dec- 

 ades, but certainly not forever. 



Salt Flat Basin, Tex. 35 Prior to 1947 ground water in the 

 Dell City area of western Texas was used only for watering 

 livestock and for supplying ranch headquarters. In the next 

 three years there was rapid development for irrigation. By 

 1949, 78 wells had been drilled, and 32 of these were used 

 to irrigate about G,000 acres of cotton and feed crops. 

 Pumpage in 1949 is estimated to have been about 18,000 

 acre-feet. In 1948 and 1949 the water levels in wells de- 

 clined at an average rate of less than half a foot a year. 



Salt Flat Basin is a closed basin in an arid region, and is 

 devoid of perennial streams. Water is pumped for irriga- 

 tion from a cavernous limestone beneath the valley fill. 

 The quantity of annual recharge to the ground-water reser- 

 voir has not been estimated. Natural discharq-e from the 

 reservoir is by evaporation from lake flats having an area 

 of 37,000 acres. The water table is less than 5 feet deep un- 

 der much of these flats, and the natural discharge may well 

 be several times as great as the pumpage in 1949. 



Optimum development is achieved when the average re- 

 plenishment is balanced by the average discharge and when 

 the discharge for nonbeneficial purposes has been reduced 

 to minimum. In most individual years, however, such a bal- 

 ance will not be achieved. Requirements for water for almost 

 any purpose are likely to be more constant from year to year 

 than the quantities of natural replenishment. When recharge 

 is large, the precipitation and stream flow are likely to be 

 above normal, so that the need for ground water may be less; 

 and the need for ground water may be greatest in dry years, 



85 Reference: Scalapino, R. A., Development of Ground Water for Irrigation 

 in the Dell City Area, Hudspeth County, Texas, Tex. 

 Board of Water Engrs. Bull. 5004, September 1950, 38 pp. 



