PROBLEMS FROM DEVELOPMENT 109 



centers of pumpage. As pumping is continued, water levels 

 will continue to decline until the inflow balances the with- 

 drawal from wells, but there is danger that part of the in- 

 flow may be water of higher salinity. Some wells are already 

 obtaining water of increased salinity, perhaps from the lower 

 part of the aquifer. There is also the possibility of north- 

 ward movement of saline water from the part of the aquifer 

 beneath the Gulf of Mexico, but there is no proof yet of 

 such encroachment. The aquifer is protected by thick, im- 

 permeable clay from direct intrusion of water from the Gulf 

 of Mexico, except in the vicinities of the larger coastal 

 streams. 



CONCENTRATED DRAFT FROM A PART OF A RESERVOIR 



The effect of pumping from a number of wells in a rela- 

 tively small area is to develop a somewhat irregular depres- 

 sion in the water surface, formed by the coalescing of the cones 

 of depression of individual wells. The depression is formed 

 by the pumping and increases in depth and extent if the rate 

 of pumping increases. It also will dwindle and finally disap- 

 pear after pumping ceases. Some war-emergency pumping 

 projects have given us a complete history of the development 

 and subsequent disappearance of such a cone of depression. 

 At the Topaz Relocation Center in the Sevier Desert of central 

 Utah, the artesian pressure was lowered more than 30 feet in 

 an area of a square mile, and more than 5 feet in an area of 

 11 square miles, by pumping 2,900 acre-feet in three years 

 from rather fine-textured aquifers in the valley fill. The cone 

 was eradicated within two years after pumping had ceased, by 

 slow movement of water within the reservoir. As another ex- 

 ample, during the war the rate of pumping at Norman, Okla., 

 increased from 2 million to 6 million gallons a day, and water 

 levels dropped 130 feet in two years; after the cessation of 

 pumping for war projects, water levels in observation wells 

 rose as much as 97 feet but have since declined slightly, proba- 

 bly because of pumping from nearby wells. 



The distinction here made between "concentrated" and 



