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Show PROBLEMS OF IMPERIAL VALLEY AND VICINITY. 9 reservoir site also exists on the San Juan River, which is the next tributary of importance, but the feasibility of this has not been established. Of the total area drained by the Colorado River, 244,000 square miles, 96,000 is drained by the Grand, the Green, and the San Juan, which, though draining less than two-fifths of the total area, furnish approximately 86 per cent of the total water supply. There is still, however, nearly 100,000 square miles below these rivers, exclusive of the Gila, which would be uncontrolled by such reservoirs. These areas, though furnishing a relatively small quantity of water, owing to their aridity, are yet of such extent and declivity that they furnish occasional floods of magnitude from direct precipitation, due to which their control is important from the standpoint of the flood menace. In the study of this problem it has been demonstrated, that for several reasons it is desirable to have a reservoir below the Grand Canyon of the Colorado, which will intercept most of the drainage of the Colorado River and, therefore, be a more complete solution of the flood-control problem. This method of control is important for other reasons. The large areas of very fertile and valuable lands now developed and being rapidly developed require immediate relief by extension of storage for irrigation, and if such storage is constructed in the upper basin it will of course be operated in conformity with the requirements of irrigation in the lower valley as nearly as this can be predicted, but a large percentage of the water will be lost owing to the great distance and the impossibility of predicting the exact requirements a month or more ahead. In order to provide against embarrassing shortage, it will be necessary to turn out at all times sufficient water to provide for the most extreme conditions that may occur, but which seldom do occur, and this will mean that nearly all the time a large amount of water will be flowing to wTaste. A large part of this waste can be obviated by an adequate reservoir on the lower river. In addition to the above waste, any water supply appropriated above for use in the lower valley would not be available for irrigation in the upper valley. The most feasible sites occur at points where this would be an objection to such use, because it would leave in an arid state lands that might otherwise be irrigated in the upper basin. Such a result would be a distinct waste of resources, as investigations show that there is a sufficient quantity of water to furnish an adequate supply to all of the lands in the basin that can be feasibly reached by gravity or reasonable pumping lifts. There will, of course, be local exceptions to this where the areas can be reached only by tributaries in which the local supply is insufficient, but this is aside from the main question. In addition to the above waste the regulation of waters from the upper river in accordance with irrigation needs in the lower valley would be distinctly out of harmony with the best use of these waters for power in the canyon regions where the power resources predominate. In the upper and lower regions of the Colorado Basin irrigation interests should and must predominate, although power resources are very important. In the middle or canyon region of the basin |
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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] : |