Page 107


Page 107
Colorado River problem
Is Part Of,8
Full text
412 L. C. HILL ON THE COLORADO RIVER PROBLEM Even if careful and extended tests should show sufficient strength and resistance to percolation to warrant the erection of a high dam, this sandstone is unsuitable for use in the construction of either a rock-filled or a masonry dam. The aggregate would have to be obtained several miles down stream from the dam site. In his conclusions, the author has stated that a high dam should not be built in Boulder Canyon or Black Canyon because the ultimate power development under the U. S. Bureau of Reclamation plan would be curtailed by 300,000 h.p., due to the loss of 80 ft. of head between the Boulder Reservoir and Diamond Creek. The selection of Black Canyon as the site of a storage dam should not be condemned arbitrarily because the Federal Power Commission believes that too high a dam is provided in the preliminary plans of the U. S. Bureau of Reclamation. In all the plans proposed by the author, he has considered that the elevation of the head-water above each dam should equal the tail-water level of the next dam. The least lowering of any reservoir must result accordingly in the loss of just that amount of available head in the development of power. The requirements for irrigation in the Lower Basin will seldom correspond to the quantity of water that will be released from the upper storage reservoirs for the development of power. Consequently, re-regulation of the water released for power must be effected in some reservoir at the lower end of the Canyon Section. As this re-regulation will result in unavoidable fluctuations in the level of the lowest storage reservoir, provision must be made in the ultimate development to prevent a corresponding loss of head and power. It has been suggested by Mr. E. A. Hill that a dam, which would be sufficiently high to back water to the foot of the power dam at Diamond Creek, should be constructed ultimately across the upper end of Boulder Reservoir, probably at either Spencer Canyon or Bridge Canyon. The normal low-water level in Boulder Reservoir should correspond to the river level at this intermediate dam, and during periods of high water this dam should be partly submerged. In spite of inevitable fluctuations in the level of Boulder Reservoir, it would be practicable to use in the development of power all the head between these reservoirs by the installation of variable head turbines arranged to operate when submerged as much as 100 ft. Furthermore, this plan would eliminate the loss of 80 ft. of head below Diamond Creek, cited by the author as one of the main objections to a high dam at Boulder Canyon or Black Canyon. It will be many years before the construction of this intermediate dam becomes necessary, but the speaker believes that it should be considered as part of the ultimate development on the Colorado River. It would not be difficult to construct; the flow of the river from above would be under control; and Boulder Reservoir would periodically be low enough to unwater the dam sites in Spencer and Bridge Canyons. In order that the maximum beneficial use may be made of the waters of the Colorado River, a large amount of storage to equalize the flow over several years must be provided for irrigation as well as for power. Although the

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