PROBLEMS FROM DEVELOPMENT 159 



vagaries of natural precipitation and stream flow. The John 

 Martin reservoir can give more uniform flow from year to 

 year than the natural stream, through holdover storage. The 

 ground-water reservoir along the watercourse also cushions 

 the effects of alternate excess and deficiency of stream flow. 

 Many wells are pumped only when water is needed to sup- 

 plement inadequate stream supplies, and most wells are 

 pumped more heavily in drought than in wet periods. That 

 water is pumped from underground storage. At some wells 

 the pumped water may be replaced quickly by river infiltra- 

 tion; at others the replacement may be delayed for several 

 months or even several years, until the river is at higher stage 

 or until local precipitation is more abundant. In the ab- 

 sence of ground-water studies in the area, it is not possible 

 to say where ground-water development might cause direct 

 depletion of stream flow and where such development might 

 depend instead upon recharge during periods of surplus sup- 

 plies; but it is likely that in many places the ground-water 

 reservoir could be manipulated like the John Martin reser- 

 voir, filling during flood stages and drawn upon in time of 

 need. 



By analogy with the Kansas part of the Arkansas Valley, 

 where ground-water conditions are known, it is likely that 

 pumping of ground water is partly responsible for the de- 

 pletion in flow of the river as it flows across eastern Colo- 

 rado. Wells divert water from the underground portion of 

 the watercourse just as canals divert water from the visible 

 supplies in that watercourse. However, the diversions from 

 the ground-water reservoir may or may not cause an im- 

 mediate depletion in stream flow, for the depletion may be 

 delayed until the stream is at flood stage. 



The Arkansas River compact is not intended to discour- 

 age further development of the water resources, and the 

 water that spills past Garden City in most years can be a 

 basis for additional development of both surface and ground 

 water. The compact specifies, however, that such develop- 



