PROBLEMS FROM DEVELOPMENT 85 



from wells for irrigation began in 1930, chiefly to supple- 

 ment the surface water in years of low flow; surface water 

 has been preferred when available because of the deleterious 

 effect upon the irrigated lands of sodium in the ground 

 water in parts of the valley. The pumpage from wells varies 

 from year to year depending upon the amount of water 

 available from the stream: in 1948, when 75,000 acre-feet 

 was diverted into canals, 110,000 was pumped from wells; 

 in 1949, the river furnished about 168,000 acre-feet, and 

 pumpage dropped to about 40,000. 



The ground-water reservoir of Safford Valley is part of a 

 watercourse in which both surface water and ground water 

 are moving toward Coolidge Reservoir. By pumping, it has 

 been possible to obtain almost as much water for irrigation 

 in the valley during dry years as in normal years, but since 

 this pumpage necessarily depletes the outflow from the 

 valley, the water shortages during droughts are enhanced 

 for downstream users. Many of the water rights in Safford 

 Valley antedate those for downstream use, and particularly 

 those which are dependent upon storage in Coolidge Reser- 

 voir, constructed in 1928. On the other hand, part of the 

 water in Coolidge Reservoir is used on Indian lands having 

 rights recognized as antecedent to those in Safford Valley. 



The bottom land of the Gila River is covered by a rank 

 growth of vegetation. In a 46-mile reach of the river (35 

 air-line miles) in lower Safford Valley, there is about 9,300 

 acres of salt cedar, baccharis, cottonwood, and mesquite, all 

 users of large quantities of ground water. Detailed studies 

 in 1944 showed that the vegetation in the lower two-thirds 

 of the valley wasted 28,000 acre-feet of water, of which 

 23,000 was from the ground-water reservoir. The total waste 

 in the valley was about 50,000 acre-feet in 1944. About 75 

 per cent was transpired by salt cedar, an import from the 

 Mediterranean region which is rapidly supplanting the na- 

 tive water-loving plants in the Southwest, using more water 

 than any of them. 



In addition to wasting valuable water, these plants in- 



