RECLAMATION OP ARID LANDS BEADLE. 475 



SALT RIVER PROJECT, ARIZONA. 



In Arizona the flow of Salt River has been utilized to irrigate 

 nearly 200,000 acres of fertile land surrounding the State capital. 

 Storage is provided about 80 miles above Phoenix by the famous 

 Roosevelt Dam, a rubble masonry arch in the river canyon 280 feet 

 in maximum height and 1,125 feet along the crest. This gives a 

 reservoir capacity of 1,367,300 acre-feet, or over 400,000,000,000 gal- 

 lons. A notable event in the history of the project occurred in April, 

 1915, when, four years after completion of the dam, the reservoir was 

 filled and for the first time water passed over the spillways (pi. 4). 

 The structure stood the test perfectly, and, excepting some erosion 

 of the spillway channels, the excess flood water was discharged with- 

 out harmful effect, leaving sufficient storage to insure the project 

 water supply for several years. Stream flow records for 25 years 

 indicate that, with the erratic run-off of Salt River, the reservoir 

 may be expected to fill by floods at irregular periods, but that an 

 occasional series of years of lean run-off will empty it again, causing 

 a temporary shortage of water, followed by another period of heavy 

 run-off and a full reservoir. The study of the discharge of the 

 streams of our arid region shows a tendency to these cycles of rela- 

 tively wet and dry periods, but with records of 30 or even 50 years 

 it is quite impossible to formulate any law as to their recurrence 

 or predict the time when strict economy in the use of water will next 

 be necessary. Some broad-minded men regard these occasional years 

 of scarcity as a benefit. A plentiful supply of irrigation water 

 tends to encourage overuse and careless handling, resulting in waste 

 and rise of ground water, often ruining the lower farm lands by 

 seepage and resultant concentration of alkali. The periodic year of 

 scarcity may therefore be a blessing in disguise, forcing better prac- 

 tice in the use of water and demonstrating the truth that beyond a 

 certain moderate use a greater supply means an actual reduction in 

 the crop value. 



From Roosevelt the stored water is passed 60 miles down the river 

 channel to Granite Reef, where the diversion dam turns it into canal 

 systems north and south of the stream. Over 700 miles of main 

 canals and laterals have been excavated to distribute the water to 

 the farmers. The opportunities for hydroelectric development cre- 

 ated by the construction of the irrigation works have been utilized 

 by building power plants at the base of Roosevelt Dam and at sev- 

 eral points in the canal system where necessary drops afford good 

 heads. Transmission lines have been built, delivering power to the 

 several towns on the project, including the city of Phoenix, where 

 it is used for lighting and manufacturing, and to near-by mining 

 industries, to which the surplus is sold. The receipts from power 

 sales are credited to the project, working a reduction in the total 



