10825 Water Supply Alternative Summary Phase 2 Assessment January 2008 Draft

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Recovery Program. However as outlined above, the 10825 Water may be of relatively minor importance compared to other elements of the Recovery Program, and all of alternatives recommended herein would supply 10,825 acre feet of water to the 15 Mile Reach in a timely manner. 6.2 TIMING OF 10825 RELEASES f) Recovery Program water demands commonly occur from July through October when minimum flow targets in the 15 Mile Reach are not met. g) Under existing operating conditions, 10825 Water will provide the most benefit to the endangered fish if all or a substantial portion of the water can be released in July and August, prior to the time that Green Mountain Reservoir HUP surplus water becomes available to use in September and October. Because the HUP Surplus provides over/2 to 3/a of all the Recovery Program water available in most years, it's important to spread HUP water out over the longest period possible. The 10825 Water and the Ruedi Reservoir "5 & 5" Water are the primary Recovery Program water sources available in July and August. The demand for additional Recovery Program water supplies (including 10825 Water) is often reduced by the time any Green Mountain surplus is available, which occurs commonly in early September. h) If the Green Mountain HUP surplus declaration could occur earlier in the year, 10825 Water releases could be spread out over the July through October period which could maintain a consistent flow rate from all facilities to the 15 -Mile Reach. This would result in smaller instantaneous releases of the 10825 Water, and would reduce negative impacts that may be associated with releases of this water from headwater facilities. i) A tool or process to forecast probable stream flow conditions in the 15 Mile Reach would allow the more efficient delivery of all sources of Recovery Program water, including the 10825 Water. This process could be used to (1) forecast flow targets for the 15 Mile Reach (i.e. dry or wet year targets) and (2) forecast the amount of Green Mountain surplus water that may become available. The existing process for evaluating these issues is necessarily conservative, and as a result, all of the available Recovery Program water is often not used, or is released in a less than optimum schedule. 6.3 COLORADO RIVER — HEADWATER IMPACTS j) The only headwater reach of the Colorado River that would markedly benefit from the release of 10825 Water is the Colorado River from Lake Granby to Troublesome Creek. Because the geometry of the river channel is small, the addition of 10825 Water would 10325 Pater Supply Stud, Pease 2 Alternatives Assessa ent January 2008 Draft