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Show PROBLEMS OF IMPERIAL VALLEY AND VICINITY. 15 within the city limits. The demands, present and prospective, are far beyond the capacity of the city to supply with the present facilities, and this is considered the most effective and extensive pf all of the power demands. It ig desirable, of course, to extend to all customers who desire to share in this development the same privileges. The use of the name of the city of Los Angeles is merely typical of such cities as may eventually elect to share in this development. Others may later apply and should have equal privileges. Table No. 16.-Status of lands in lower Colorado Basin in the United States. Irrigable area, acres. Private. EnterecL Public. Indian. State. Southern Pacific Railroad. Total. doUonwood Island............. 4,000 1,600 1,500 4,000 27,000 4,000 110,000 78,000 18,000 44,000 16,000 4,000 130,000 515,000 160,000 5,000 72,000 33,000 Mohave Valley . 12 800 12,600 2,500 110,000 Chemehuevis Valley__ Parker project.................. Palo Verde Valley.............. 72,000 3,500 500 6,900 2,900 62,000 515.000' 6,000 12,400 32,500 2,500 19,000 800 8,500 4,800 1,100 38,200 1 300 Chucawalla Valley.............. Cibola Valley__-¦..... 2,500 1 800 Isolated tracts Yuma project ___ 9,000 1,800 Imperial irrigation district...... Imperial Valley extensions: East Side Mesa............ 1,200 200 12,100 1,000 1,200 1,400 3,400 9,300 148,100 700 3,800 14,300 11,400 100 8,300 300 4,400 1,600 1,200 2,400 36,900 6,700 Dos Palinas Coachella Valley............ West Side............ Total in United States1... 690,000 87,700 227,400 145,600 22,000 47,200 1,220,000 *Late estimates from State engineer show 30,000 acres additional in lower basin in Nevada. CONSTRUCTION METHODS. Borings made in 1903 and 1904 on the lower river showed that at Bulls Head, Williams Fork, Picacho, and other points tested the subterranean channel of the river had been eroded to a great depth, so that the foundation of dams at any of these points on bedrock was considered infeasible. In view of this fact and of the silt problem, some engineers were led to conclude that storage at any point in the lower basin of the Colorado River was not feasible. Further consideration, however, led to the evolution of a plan for building a high dam without excavating the river to bedrock, which, owing to the peculiar topography of Boulder Canyon, seemed to be at least worthy of consideration. At this point the canyon is about 300 feet wide at the river level, and cliffs of massive granite reach upward nearly vertical to a height of over 2,000 feet above the river. Plans were evolved for a loose-rock dam at this point constructed by the following method: It is proposed to pierce the cliffs with large tunnels on each side of the dam site a short distance above the low level of the river at medium stages in order that the river might be diverted through these-tunnels at moderate stages, if desired. These tunnels were to be equipped with controlling works. For a dam, say, 600 feet above the river level it was proposed to provide slopes for a rock-fill dam of three to one on each side when counted from bedrock to summit |
