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<br />CHAPTER IV - WATER <br /> <br />The water supply developed through the Summit system will not <br />be change~ as a result of actions recommended in this report. The <br />improvements to Summit Reservoir will allow historic operational <br />patterns to continue. This chapter describes the historic water <br />supply in general.terms; with emphasis on the supply from Summit <br />Reservoir. In-depth analysis would require considerable time <br />and is not within the scope of this study. <br /> <br />Water Requirements <br /> <br />The Bureau of Reclamation has done extensive studies on water <br />requirements for irrigated lands in southwest Colorado. These <br />studies show that the consumptive use for grain and pasture/ <br />hayland at 7000 - 7200 feet elevation are 1.11 AF/ac and 1.68 <br />AF/ac respectively. <br /> <br />The Summit irrigated land has on-farm irrigation efficiencies <br />of about 45% and delivery system losses of about 10%. The result <br />is a water requirement from the reservoirs of 2.71 AF/ac for grain <br />and 4.11 AF/ac .for pasture/hayland. . Since the irrigation effi- <br />ciencies are low there is a lot of runoff from farms which can be <br />diverted and reused. There is no data on this so a figure of 10% <br />of the water applied was assumed to be reusable return flow. The <br />associated water requirements are reduced to 2;44 AF/acfor grain <br />and 3.70 AF/ac for pasture/hayland. <br /> <br />Finally, the per acre values can be reduced further to. account <br />for effective precipitation. The grain requirement can be reduced <br />to 2.01 AF/ac and the pasture/grassland to 3.19 AF/ac. There is", <br />q.bout five inches of effe'cti ve precipitation in. the average year. <br /> <br />Surface Water'Supply <br /> <br />The Summit water supply is almost entirely the result of <br />diversions from Lost Canyon Creek and its tributaries by Turkey <br />Creek Ditch and Lost Canyon Ditch. the drainage areas above the <br />three reservoirs are very small and do not yield significant <br />amounts of water. Both Turkey Creek, and Lost Canyon Ditches have <br />capacities of about 130 cfs eaGh. Turkey Creek Ditch is quite' <br />long and collects water from Lost Canyon Creek and several tribu- <br />taries before it fills Joe Moore Reservoir. A gage is located at <br />the inlet to Joe Moore. The ditch then extends westward to Summit <br />Reservoir; some lands are irrigated from the ditch in this segment.' <br /> <br />Lost Canyon Ditch is a direct diversion, short compared to <br />Turkey Creek Ditch, from Lost Canyon Creek into Summit Reservoir. <br />A gage is located on the ditch as it enters Summit Reservoir. <br /> <br />Records have been kept on the Summit system for decades but <br />those reoords are spotty and the data does not correlate well. <br /> <br />-12- <br />