94 CONSERVATION OF GROUND WATER 



draft on the ground-water reservoir was generally less than 

 3,000 acre-feet a year. The natural replenishment was ample 

 for this amount of development, and in addition the natu- 

 ral discharge by evapotranspiration was of the order of 

 5,000 acre-feet, as shown by detailed studies in 1926 and 

 1927. 



Since 1943, several new irrigation wells have been drilled 

 each year, and pumpage has increased until in 1949 it 

 reached about 40,000 acre-feet, applied to 12,000 acres of 

 land. A substantial but unmeasured part of this water re- 

 turns to the ground-water reservoir by percolation from 

 irrigated lands, ditches, and the unlined reservoirs into 

 which water is pumped prior to use. Nevertheless, there has 

 been some depletion in ground-water storage, and since 

 1946 the water table has dropped 1 to 2 feet a year over ex- 

 tensive areas. 



The areas of natural discharge by evapotranspiration are 

 generally unsuitable for growing crops because of salt ac- 

 cumulation in the soil. Pumping in the newly developed 

 areas can reduce this natural discharge only by lowering the 

 water table sufficiently to prevent movement of water to the 

 areas where the natural discharge occurs, a lowering which 

 would be as much as 75 feet in some places. This method in- 

 volves considerable depletion of storage, which means that 

 pumping in the early stages of development can be at a rate 

 substantially greater than the natural replenishment, and 

 therefore greater than the yield which can be sustained per- 

 ennially. It is possible also that the water now wasted by 

 vegetation can be salvaged only by pumping from such great 

 depths that the cost is prohibitive. 



The state of Utah in 1946 proclaimed the southern part 

 of Escalante Valley closed to additional appropriation of 

 ground water for an indefinite period, not because the 

 available water supplies were known to be entirely appro- 

 priated, but because time was needed to determine the ef- 

 fect of pumping from wells already completed or author- 

 ized for construction, and the relationship between draft 

 and replenishment. Studies since that year have shown that 



