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Show PROBLEMS OF IMPERIAL VALLEY AND VICINITY. 35 local stream flow. It also considers return flow in the annual regime observed on Reclamation Service projects.^ The effect of irrigation in the upper basin bit discharge in the lower river will be a smoothing out of seasonal and annual irregularities, both by storage in hold-over reservoirs and storage in the ground beneath irrigation projects. In the years 1902, 1903, and 1904, the run-off was so small that in the upper basin the average project would hardly have had half its supply and this would have reduced consumptive use in those years by possibly 25 per cent. This has been taken account of in calculations. The acreages estimated as irrigable include a few duplications; the most conspicuous example is that of the water supply of the Virgin River. This river rises in Utah and receives most of its water supply in that State. It is possible to ,use this water in Utah, Arizona, or Nevada. All three States propose such use to an extent that in the aggregate will greatly exceed the available water supply The acreages in all are included, but only of course the actual w&ter supply of the Virgin River. Table No. 6.-Estimated future depletion by development-Upper basin. Month. Irrigation. Diversion out of basin. Total. January... February.. March..... April...... May....... June__... July....... August___ September. October... November. December.. Acre-feet:^ 20,000 30,000 Acre-feet. 50,000 340,000 1,118,000 1,592,000 635,000 178,000 41,000 +36,000 +47,000 +10,000 22,000 148,000 75,000 32,000 19,000 16,000 7,000 Acre-feet. - 20,000 - 30,000 - 50,000 - 340,000 -1,140,000 *-1,740,000 710,000 210,000 60,000 ', 20,000 40,000 10,000 3,913,000 317,000 4,230,000 Consumption per acre, 1.54 acre-feet. 1902, 1903, and 1904, 3,180,000 acre-feet. Estimated depletion for INCREASED EVAPORATION FROM POSSIBLE RESERVOIRS FOR POWER IN CANYON REGION. At first thought it would seem that power development above would not decrease average water supply below, but with conditions for power development on the Colorado as they are the toll of water will be large. Head for power will be, developed mostly by constructing dams in the river channel, and these will create large areas, of warter surface to be exposed to the evaporation of this intensely arid region. Large reservoirs also must be built to equate the discharge for these dams. |
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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] : |