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Show PROBLEMS OF IMPERIAL VALLEY AND VICINITY. 45 (a) Grand River (principal tributary to, Colorado): Gage inJL884 read at peak was 18.5; highest since, in 1909, was 15, indicating a flood with possibly twice as high a peak as the 1909.. (b) Cache La Poudre River (heading on opposite side of Rockies from the Grand): 1884 was highest year ever recorded. The next highest was 1909. In May and June of 1884 total discharge was 68 per cent greater than in 1909. (c) Columbia River was higher in 1884 than in 1909, altnougirthe difference for entire year was only 7 per cent. The inference from the foregoing is that there was surely a high flood on the Grand, that it may have continued through May and June, and that probably heavy discharge occurred throughout the West, making it possible that the Green and San Juan both were in heavy flood at the time. A 50 per cent greater flood continued as long as that of 1909 would require for control to 50,000 second-feet storage capacity of 12,000,000 acre-feet for present conditions on the river and 7,000,000 acre-feet for ultimate conditions. A baffling feature of estimate of flood control necessary is the great variation in discharge with the same gage. It would be conservative, however, to estimate that a 9,000,000 acre-foot capacity always reserved for flood control would bring the largest flood down to 50,000 second-feet and a 5,500,000 acre-foot capacity would reduce the largest flood to 75,000 second-feet. '¦.'., Necessity for building capacity specifically for flood control decreases as reservoirs approach that Capacity necessary for complete control of the discharge, and if development takes place as outlined, floods ,on the Colorado will be taken care* of without reservation of much capacity in Boulder Canyon reservoir for this purpose. FLOOD CONTROL ON THE GILA. Control of the Gila for floods can be completely accomplished only at Sentinel reservoir site. The worst flood of record occurred from January 20 to February 3, 1916, during which time the peak reached almost 200,00Q second-feet and the entire discharge Was 2,373,000 acre-feet. ' / The following shows the storage necessary to reduce the discharge to various figures: Discharge (in second-feet): Storage necessary. 10,000............................................................2,100,000 20,000............................................................ 1, 800,000 30,000.........................*.................................. 1, 500,000 40,000........................,................,.................. 1, 200,000 50,000...........................................'.................•- 900^000 With control of the Colorado River by reservoirs on the tributaries and with floods from the Gila probably occurring at the same time that floods occur from the intermediate basin below the San Juan, there would be necessity for reducing the floods of the Gila perhaps to as low as 10,000 second-feet in order to avoid simultaneous floods. But with the Colorado River reservoir at Boulder Canyon such necessity would not exist, and the discharge could be permitted to |
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Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : |