142 CONSERVATION OF GROUND WATER 



decreasing yield of wells since its first well was drilled in 

 1926, but here the problem has been one of reduction of 

 inflow to the well casings because of incrustation. There 

 never has been any lack of adequate replenishment from the 

 nearby Ohio River, and wells of different design are capable 

 of a sustained production of more than 9 million gallons 

 a day. 



Des Moines, Iowa. 67 The public water supply for the city 

 of Des Moines has for 80 years been derived from ground 

 water in the watercourse of the Raccoon River. Currently 

 more than 20 million gallons a day is pumped to serve a 

 population of about 190,000; this is twice as much as was 

 pumped in 1922, and four times the demand in 1910, when 

 the population was about 80,000. Since 1910 the city has 

 practiced artificial recharge of the ground-water reservoir 

 from which it takes its supply and thus is one of the real 

 pioneers in controlling storage of water underground. 



The ground-water reservoir of the Raccoon River Valley 

 is in gravel and coarse sand about 20 feet thick, overlain by 

 several feet of permeable soil. The city obtains its water 

 from an infiltration gallery paralleling the river and about 

 3 miles long, which can lower the water table a maximum of 

 6 feet below the low-water level of the river. Studies have 

 shown that as much as 90 per cent of the water produced by 

 the gallery may be derived by infiltration from the bed of 

 the river, and the rest is from downward percolation of local 

 precipitation. The rate of river infiltration is substantially 

 reduced when the river bed is covered with silt. 



As early as 1910 the city was troubled by insufficient water 

 supply during extended rainless periods when the river was 



67 References: Burdick, C. B., Basic Principles of Ground Water Collection, 



Proc. Am. Water Works Assoc, p. 257, 1913. 

 Maffitt, D. L., Artificial Flooding Builds up Ground-water 



Yield, Water Works Eng., vol. 96, no. 22, pp. 1230-1232, 



1943. 

 Board of Water Works Trustees, Description of Des Moines 



Water Works System (1945), and Annual Report for 1949. 



