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Show 44 PROBLEMS OF IMPERIAL VALLEY AND VICINITY. other reservoirs. Draft on Juniper next would provide for four more, and Flaming Gorge, acting as a holdover reservoir, could provide approximately for all the rest except 1903 and 1904, when shortages to the full amount shown would be felt, of 17 per cent and 33 per .cent, respectively. What has been said as to power under plan 1 applies more cogently to this because the value of all power sites on the entire Yampa, while not destroyed, would be seriously impaired because they could use only Little Snake River water. On the Green, until the Yampa is reached, they would be totally destroyed and seriously impaired below that. In addition, the upper reservoirs will provide insufficient flood control of the Lower River. FLOOD CONTROL ON THE COLORADO. Floods in the Ipwer Colorado come from three sources: (a) The Gila Basin; .(&) the intermediate area between the San Juan and the Gila; (fc) the headwaters of the Green, Grand, and San Juan. The first gives floods in January and February, as a rule, but they are very erratic. They are also heavier than floods from other sources, but are of short duration. The second area gives floods of similar nature and they are possibly as severe as from the Gila, and they are likely to come at times wnen they might coincide with the Gila and thus be especially destructive. In the period of record there was one flood of about 70,000 second-feet in February, 1920, most of which probably came from this source, but to date records are not available from the upper streams by which the source can be determined. Floods from the third area, the upper tributaries, occur practically every spring and are of long duration. They start with the melting snow on the slopes of the Continental Divide and its spurs in Colorado, Utah, and Wyoming. Floods from the first source can be controlled only by a reservoir near the mouth of the Gila, from the second by a reservoir below Virgin River, and from the third by reservoirs either on the major tributaries or lower down on the main river. A reservoir below the Virgin would control floods from both areas 2 and 3. Flood control by storage will have to be supplemented by levees. It is estimated that if the floods could be controlled to a maximum of 50,000 second-feet a satisfactory levee system could easily be maintained. When ultimate development takes place the floods will be reduced by storage for irrigation in the upper basin, and by storage in canyon area for power. In round figures the flood control necessary under present conditions is 8,000,000 acre-feet. There is likelihood that more severe floods occur. So far as gage records give information, exceptionally high water occurred in 1884, 1905, 1906, 1907, and 1909, with 1909 the highest during the spring floods. Gage heights at Yuma are not entirely conclusive, as there is some evidence that the river bed raised 3 feet at Yuma between 1884 and 1909, which, if true, would indicate a very heavy flood in 1884. This would corroborate other evidence bearing on 1884, which is as follows: |
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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] : |