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<br />CHAPrER V <br /> <br />ALTERNATIVES STUDIED <br />(Tomichi Creek Unit) <br /> <br />""'"' <br />'""" <br />CD <br />.-.j <br /> <br />Water utilization <br /> <br />'-. <br /> <br />Water Requirements <br /> <br />Based on an irrigation efficiency of 30 percent, the irrigation <br />water requirements are estimated at an average of 43,800 acre-feet annu- <br />ally or 4.3 acre-feet per acre. Approximately 24,500 acre-feet of the <br />supply is currently available. The remaining 19,300 acre-feet would be <br />required from the project. <br /> <br />Operation <br /> <br />Water would generally accumulate in Elko Reservoir from October <br />through May. When possible, storage would be carried over from high to <br />low water years. Releases for irrigation would normally be made from Ma(r <br />through September with peak releases in June. Releases would be made to <br />sustain the fishery flows in Tomichi Creek below the dam, with a minimum <br />flow from November tr~ough April of 20 cubic feet per second or the in- <br />flow, whichever is less. The reservoir data are s1.ll!lmarized in the table <br />on the following page. <br /> <br />With the Tomichi Creek Unit, irrigation supplies would be increased <br />by an average of 15,100 acre-feet annually at diversion points. The in- <br />creased supply would include approximately 7,000 acre-feet of storage re- <br />leases and 8,100 acre-feet from direct streamflows not presently utilized <br />and return flows. Annual irrigation shortages would average about 9.6 <br />percent compared with existing shortages of 29.4 percent. With the unit <br />in operation over the 1952-69 study period, critical shortages would have <br />occurred in 1955 and 1967 and would have amounted to 51 and 57 percent, <br />respectively. <br /> <br />The flows of the Colorado River system would be depleted by an aver- <br />age of 4,800 acre-feet annually. According to the Environmental Protec- <br />tion Agency, the salinity at Lake Mead would be increased by about 0.4 <br />milligram per liter and the economic impact to water users below Lake <br />Mead would amount to about $25,000 annually on the basis of 1972 prices. <br /> <br />Water rights for the Tomichi Creek Unit have been obtained by the <br />Colorado River Water Conservation District and transferred to the Upper <br />Gunnison Water Conservancy District. The rights have a decree date of <br />December 15, 1961, and a priority date of November 13, 1957. The water <br />rights were obtained for an earlier plan of development and would require <br />adjustment for the present plan. The changes would include changes from <br />Monarch Reservoir to Elko Reservoir and from the South Crookton Canal to <br />the Crookton Canal. <br /> <br />45 <br />