110 CONSERVATION OF GROUND WATER 



"dispersed" development is recognized as arbitrary and is 

 chiefly to set apart those areas where a redistribution of wells 

 might solve the problem of excessive pumping lifts in the cen- 

 ters of existing cones of depression. Such redistribution would 

 serve little or no purpose in the Dakota sandstone area, be- 

 cause pressure heads everywhere have been reduced so much. 

 However, in the Chicago-Milwaukee area and in the rice areas 

 there are localities of concentrated pumping within the 

 broader region where water levels have declined. Wells in the 

 centers of those deep cones of depression have far greater 

 pumping lifts than those elsewhere in the region. 



In several other localities large quantities of water are 

 pumped from closely spaced wells, all at a distance several miles 

 from the recharge area. Memphis, Tenn., El Dorado, Ark., and 

 the Mill Creek Valley, Ohio, are listed as examples. 



Memphis, Tenn.,* 1 pumps about 10 million gallons a day, 

 or about one-twelfth of its total water supply, from a sand 

 aquifer 1,200 to 1,500 feet deep. Most of this water is 

 pumped from wells within the city limits and about 50 miles 

 from the recharge area. Since 1924 more than 50 billion 

 gallons of water have been pumped out, and detailed hy- 

 drologic studies indicate that practically all has been taken 

 out of artesian storage; for the cone of depression has not 

 yet extended to the recharge area, and there has probably 

 been no appreciable increase of inflow from that area. Water 

 levels have declined about 50 feet in the past 25 years, but 

 the quantity of water pumped out is small compared with 

 the total storage in the reservoir. The water levels will con- 

 tinue to decline until the cone of depression has expanded 

 to the recharge area and until the draft is balanced by in- 

 creased inflow. 



41 References: Schneider, Robert, and E. M. Gushing, Geology and Water- 

 bearing Properties of the "1400-foot" Sand in the Memphis 

 Area, U.S. Geol. Survey Circ. 33, 1948, 13 pp. 

 Kazraann, R. G., "The Water Supply of the Memphis Area," 

 U.S. Geol. Survey, Duplicated rept., September 1944, 66 pp. 



