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<br />SUMMARY <br /> <br />September flows would be 897 ft'/s for alternative A, 730 ft'/s <br />for B, 637 ft'/s for C, 730 ft'/s for E, and 730 ft'/s for F. <br />Minimum streamflows would be 300 ft'/s for all alternatives, but <br />the frequency of 300 ft'ls flowsw.oulcl increase significantly with <br />development alternatives. <br /> <br />A monitoring system would be operated to assure maintenance of <br />instream flows as well as protection of irrigation supplies. In <br />addition under alternative F, additional flows would be bypassed <br />to the Gunnison River during winter operations if adverse icing <br />conditions develop. AlternativeF also would release up to <br />1,000 acre-feet of additional flow to the Uncompahgre River via <br />the South Canal during the summer. <br /> <br />The operation of the facility would result in a decrease in <br />Uncompahgre River flows in some reaches and increases in other <br />reaches. Streamflows in the Uncompahgre River entering Montrose <br />would be reduced by 75 percent for all of the development <br />alternatives. Streamflows in the Uncompahgre River downstream <br />from the proposed tailrace would be increased by 339 percent for <br />alternative B, 364 percent for alternative C, 318 percent for <br />alternative E, and 336 percent for alternative F. <br /> <br />Diversions from the Gunnison River would be curtailed under all <br />alternatives, including no~action, during periods of flooding <br />along the Uncompahgre River. Under the development alternatives, <br />local flooding and severe local erosion would occur in case of <br />catastrophic penstock failure. <br /> <br />Irriqation <br /> <br />. <br />Operation of the development alternatives would not affect the <br />amount of water diverted for irrigation use within the study <br />area, including private irrigation diversions as well as the <br />UVRP. The Montrose and Delta Canal and the Loutzenhizer Canal <br />would recerve the majority of their water supply from the <br />Uncompahgre River with development. Under the no-action <br />alternative, about 59 percent of the water supplies delivered to <br />these canals would be derived Lrom the Gunnison River. Under any <br />of the development alternatives, this figure would be reduced to <br />about 35 percent. Senior water rights for private irrigation <br />diversions along the Gunnison and Uncompahgre Rivers would <br />continue to be honored.' <br /> <br />River Morphology <br /> <br />Without development, the Gunnison River between the North Fork <br />confluence and Delta would be expected to become narrower and <br /> <br />S - 5 <br />