Page 109


Page 109
Colorado River problem
Is Part Of,8
Full text
414 L. C. HILL ON THE COLORADO RIVER PROBLEM site, in his opinion, is that its flowage damages may be high, as it will require moving the Town of Needles, a division point on the Santa Fe Railroad, and re-locating 15 to 20 miles of main-line railroad. He neglected to call attention to the fact that about 100,000 acres of land in the Mohave and Cottonwood Valleys would be submerged and thus eliminated from agricultural development. The principal advantage claimed for the Mohave Reservoir is based on rather fallacious reasoning. The author states that water for 50,000 acres of land would be saved if Boulder Reservoir were reduced in size and Mohave Reservoir constructed. This assertion is based on apparent differences in evaporation losses. According to Table 18, there would be, under the U. S. Bureau of Reclamation plan, an evaporation loss at Boulder Canyon of 650,000 acre-ft. per annum, or 600,000 acre-ft. more than at present, while future evaporation loss, under the author's plan, with the same flood control at Mohave, would be 490,000 acre-ft., from which has been deducted 350,000 acre-ft. as the present loss, leaving only 140,000 acre-ft. as the net loss. It is incorrect to credit all the present loss from the 72,000 acres of flooded area in Mohave and Cottonwood Valleys to the Mohave Reservoir. Flood control in Boulder Reservoir would greatly reduce the area from which evaporation would occur. This inevitable reduction should properly be credited to the Boulder Reservoir and only the remainder should be a credit to the Mohave Reservoir. Unless submerged, these valleys will be irrigated when regulation is provided, consequently the evaporation from this irrigable area cannot justifiably be deducted from the evaporation loss from the reservoir which would submerge these lands. It would be equally logical to create a reservoir out of the cultivated Palo Verde and Parker Valleys in order to eliminate the evaporation loss from these lands. In Table 33 is shown the manner in which the speaker believes these losses should be considered. For purposes of comparison, the values in Table 18 are taken as correct. This saving by the elimination of Mohave Reservoir would be about sufficient to compensate for the evaporation loss from the proposed secondary reservoir near Parker. At least the quantity of irrigation storage given must be provided below the Canyon Section, in addition to that needed for flood control and for silt accumulation, even if up-river storage is developed later, as considered by the author. Careful analysis of all the factors affecting the reduction of the water supply by evaporation shows clearly the fallacy of this objection to Boulder Reservoir. Flood Control.—The ideal reservoir for flood control would be below the last tributary of any consequence. Unfortunately, such a provision on the Colorado River is impossible below the Gila, so that the control of the Gila River floods must be by separate regulating works on that stream. It is generally agreed that reservoirs for flood control on the Colorado should be at, or below, the lower end of the Canyon Section. Consequently, discussion revolves around the selection of Boulder Reservoir or Mohave Reservoir.

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