Prehearing Statement of Colorado River Water Conservation District

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UPCO/Suinmit County Water Supply Study December 15, 2004 Study Scope The purpose of the Suminit County study is to investigate the alternatives depicted in Figure 1. The areas of investigation include the supply hydrology at each site, meaning both physical supply and the legal ability to divert, given other users' and instream flow rights. The scope also includes reconnaissance level facility design and/or review of existing engineering reports, where applicable, and estimation of probable cost. Environmental and institutional issues (other than water rights administration) are not specifically addressed in this effort except as they become obvious through study of the hydrology and facility design. Alternatives that appear favorable from a water supply and engineering perspective will need to be examined from these other perspectives at a later time. Summit County, through its Information Services Department, provided data used to study site characteristics for the water supply alternatives. For instance, calculations for reservoir capacities and dam volumes were based on contour data interpolated from a 10-meter resolution USGS digital elevation model which Boyle obtained from the County. GIS coverages from Sununit County included Land Classification and Aerial Imagery, the latter having a capture date of 1999. On the basis of these, the prospective project sites were evaluated in terms of land ownership, potential development conflicts, and inundation issues. The UPCO/Summit County Participants identified for inclusion in this study four possibilities for new storage above Dillon Reservoir: 1. New reservoir on Middle Fork Swan River 2. New reservoir on Swan River just below the confluence of Middle and North Forks 3. New reservoir on Indiana Creek 4. Re-operation of the existing Clinton Reservoir These are denoted in Figure 1 as red dots. These potential reservoirs would be subject to Dillon Reservoir's and Green Mountain Reservoir's water rights, meaning that until these two large reservoirs fill in any given season, the alternatives' storage rights would be out of priority. In average and dry years, by the time the fills were accomplished, the hydrograph would have already peaked and physical supply at the new reservoir site would be limiting. The Clinton Gulch re- operation is a non-structural alternative. It involves extending the capacity of the operating pool from 3600 af to 4200 af, by pumping up to 600 af from the current dead pool when the entire reservoir must be drawn down. Applying the current Clinton Reservoir - Fraser River Water Agreement's (the Clinton Agreement's) premise that storage should be able to provide three times the annual draft, this would raise allowable annual depletions by the Clinton owners from 1200 aflyr to 1400 af/yr.