PROBLEMS FROM DEVELOPMENT 157 



annual runoff at the Kansas-Oklahoma state line is more 

 than five times as great as that at Garden City. 



Diversions from the river for irrigation in eastern Colo- 

 rado and western Kansas account for most of the decrease 

 in stream flow in those areas. Pumping from wells for irri- 

 gation in the Arkansas River Valley has also caused a sig- 

 nificant reduction in the flow of the river. Many of the wells 

 are used to supplement surface supplies, and are pumped 

 chiefly in dry years. Total annual pumpage doubtless fluc- 

 tuates considerably and may approach 150,000 acre-feet in 

 some years. Most of the reduction in stream flow occurs in 

 Colorado, but detailed ground-water studies have not been 

 made of that part of the Arkansas Valley, and the effect of 

 ground-water development upon stream flow cannot be as- 

 sessed quantitatively. 



In Kansas ground-water studies have shown that heavy 

 pumping of ground water for irrigation, especially between 

 Syracuse and Garden City, has stopped the seepage to the 

 stream which characterized that reach under virgin condi- 

 tions and has depleted the stream to the extent that the chan- 

 nel often goes dry, particularly in the summer. Prior to 1925 

 the ground-water inflow to the stream in this reach was fre- 

 quently more than enough to offset the diversions through 

 canals and wells. In the past quarter century stream losses 

 have been recorded every year; in most years the losses have 

 been substantially greater than the canal diversions and 

 were undoubtedly caused in part by pumping from wells. 

 Infiltration of river flow into the ground-water reservoir 

 has not only replenished the water pumped for irrigation 

 but has been of considerable value in dissipating floods. In 

 recent years many floods that passed Syracuse have been 

 largely absorbed by the partly depleted ground-water reser- 

 voir near Garden City. Only the largest floods continued as 

 far downstream as Larned, and these had greatly reduced 

 crests. Doubtless the pumping from the several hundred ir- 

 rigation wells in the Arkansas Valley in Colorado has had 

 similar effects upon the flow of the river. 



