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Gypsum Loan Feasibility Outline <br />CWCB Water Project Loan Program <br />Page 17 of 33 <br />representation of the catchment's average daily runoff pattern. This scaled hydrograph <br />shows an average base flow approaching 0.5 cfs and an average peak in mid June of over <br />14.7 cfs as shown below. <br />In average years, the CWCB minimum instream flow adjudication on Antones Cabin <br />Creek will likely be the water right governing the Town's diversions through the ditch, <br />although this assessment is considered to be conservative based on peculiarities of the <br />creek which could result in even better legal availability for the Town. The CWCB right <br />is for 2.5 cfs during the spring and summer months. Integrating the portion of the <br />hydrograph above 2.5 cfs, yields about 1,095 ac-ft from around the beginning of May <br />through the first week in August. If due to basin wide demand driven increase in future <br />stress on the river system, a mainstem Colorado River call curtailed diversion as of the <br />first of July as another conservative assumption, the truncated amount would be about <br />884 ac-ft. <br />Creek Flow at LEDE Ditch Headgate <br />Projected Average Hydrograph <br />16 _ _ ___ -- -_ _ _ _ <br />14 <br />12 <br />~ ~ p 884 ao- ~ <br />c~ ~~~ I <br />C $ <br />3 ` ' <br />0 <br />~ 6 <br />4 <br />_:_ _ _ _- _ _ __ __ <br />2 <br />0 <br />1-Jan 2-Apr 2-Jul 1-Oct <br />date <br />This much has never been diverted before for several reasons. First, the existing diversion <br />structure was not set up to handle snow and ice, which together with the difficulties of <br />early season access, resulted in diversion not typically beginning until runoff had been <br />underway for as long as a month or more. Additionally, the existing physical capacity of <br />the ditch doesn't safely accommodate peak flows, the existing capacity of the reservoir <br />does not allow for storage of so much volume, and the historical demand for water <br />storage was much less. Although for these reasons less water was diverted and stored in <br />the past, it is believed based on the analysis above that after infrastructure upgrades there <br />will be about 1,160 ac-ft (276 plus 884) of water available for storage in LEDE Reservoir <br />on average. In wet years more water may be available and in dry years less water may be <br />