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Show 42 THE AU>AMERICAST CANAL. water to the Yuma mesa, on which are located about 50,000 acres of project lands. The desilting channel would then be conveying from the river to the canal about five times as much water as heretofore, and there will have to be suitable enlargement of the diverting works and more frequent operation of the sluice gates. Under cooperation with Imperial Valley the maximum diversion, as planned for the all-American canal, will reach about 10,600 second-feet. The present desilting channel has not been dimensioned either for this amount of water nor yet for that ultimately required for the Yuma project alone. It must be enlarged and extended- But the general plan of operation will remain the same. Periodically the sluice gates will be opened and the sand which has been deposited in the desilting chamber will be scoured out. It is proposed as a part of the all-American canal work to allow space for a fourth Stoney gate inshore from those now in use. The desilting basin will be widened and extended farther upstream. It will be confined between two rock-fill training walls which, while gradually spreading apart, will curve out toward the river so as to leave a wide open mouth for the inflow of the canal water. The present head gate will be replaced by a new structure of similar type having a length of about 1,374 feet. The upstream portion of this head gate will be constructed while the present one remains in service, and later the upper end of the new gate wili be put into use during reconstruction of its lower end. Based on the experience thus far at the Laguna Dam it is estimated that for desilting operations an amount of water not in excess of eight hours per week of the canals flow will be required. Whether the desilting operation will be undertaken once a week or more frequently will depend not alone on the rate at which sand accumulates in the desilting channel, but also upon the effect which the resulting irregular flow in the canal will have upon the development of power and on the demands of the irrigators. THE CANAL FROM LAGUNA DAM TO THE SIPHON DROP. For 10.2 miles from Laguna Dam the canal will carry 10,600 second-feet of water, both for the Yuma project and the Imperial Valley, in the enlarged Yuma Canal. At the lower end of this 10-mile stretch on the present canal is a structure known as the Siphon Drop, through which the Yuma project water drops about 10 feet to the lower level at which it flows across the submersible river lands to the bank of the river opposite Yuma. The 6-foot superelevation of the canal banks will be such that with perfect safety the ordinary water-surface elevation could be increased. Furthermore, the operation of the system will probably require that dredges be kept in operation at certain points of the canal, and these can at any time, |
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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] : California exhibits. |