AZ vs. CA:24 California Exhibits, Vol. XXIV; Miscellaneous

page 168

168 PROBLEMS OF IMPERIAL, VALLEY AND VICINITY. Water supply and irrigation requirements. [Acre-feet.] Stream flow. Irrigation demand. Demand on storage for- Month. Acre-feet per acre. Acre-feet for-^ 125,000 acres. 400,000 acres. 125,000 acres. 400,000 acres. Apri]......... 183,000 266,000 292,000 108,000 87,000 75,000 363,000 0.20 .70 1.00 .80 .60 .20 25,000 88,000 125,000 100,000 75,000 25,000 •80,000 280,000 400,000 320,000 240,000 80,000 May........... 14,000 108,000 . 212,000 153,000 5,000 June............... July................. August......... September........ October............. Total............ 1,374,000 3.50 - 438,000 1,400,000 492,000 A project up to 125,000 acres could apparently operate without storage and encounter no shortages except in subnormal years, when shortages would occur but not severe enough to warrant reduction in acreage. For a project of 400,000 acres at least 1,000,000 acre-feet of storage would be necessary to avert frequent shortages. The hold-over capacity of 500,000 acre-feet as compared to demands in an average year would obviate shortages in most years. In a period of low run-off like 1900-1904, shortages would occur due to lack of supply in the river but their elimination by means of storage would probably not be feasible. Storage.-The Turley reservoir site at the diversion is estimated to have a capacity of 1,100,000 acre-feet. It would undoubtedly be an expensive reservoir. Other reservoirs above the1 diversion which might be used in whole or in part for this project are as follows: Stream. Site. Capacity. Pine River...... Do.......... Piedra River___ Do.......... San Juan River. Drv Creek. Vallecito.. Truiillo... Piedra___ Juanita... Acre-feet. 85,000 100,000 90,000 0) 90,000 Total (Including Piedra). 365,000 1 Capacity unknown. Conclusion.--This project from present highly preliminary data and plans will be very costly, and from this standpoint may not develop for many years, although the water supply is sufficient. Owing to the probable marked difference in total construction cost of a project of 125,000 acres without storage limited to the easterly side of Canon Chaco and one of 400,000 acres involving large storage, the former has been placed in class B and the balance of the project in class C. MANCOS RIVER AND M'ELMO CREEK. There are no definite projects on this stream, but present water supply, augmented with a small amount of return flow from the Montezuma project, is expected to be spread over a larger acreage than at present, resulting in an increase in irrigated area of 10,000 acres. The additional water used consumptively will probably not exceed 1 acre-foot per acre.