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UPCO Final Report Executive Summary 000375 May 29, 2003 Page viii flow levels and kayak low-flow levels. Reservoir levels during the summer recreation season and flows in the Blue River below Dillon are influenced primarily by water demands on the Denver System. Green Mountain Reservoir and the Blue River Below Green Mountain: P ACSM results indicated that flows in the Blue River below Green Mountain are usually above the CWCB and fish minimum levels under all scenarios. However, kayaking flows were below the minimum and optimum levels under current demands in all months except June and July and under future demands in all months except July. \f. Impacts of 2002-2003 Drought As previously discussed, the 1947-1991 study period for the UPCO model includes a number of wet, average and dry years. The study period includes the 1954-56 and 1977 droughts, which have historically been used by water planners for estimating the "firm" yield of their water supplies. The participants of the study realize that the current 2002- 2003 drought may present conditions even more severe than the past droughts. The participants also recognize that a number of conditions have occurred to-date during the 2002-2003 drought that may present unique new challenges which need to be considered in the future. These specific conditions include the following: 1:1 Streamflows in certain areas of the Colorado River Basin and its tributaries were lower than in previous droughts. 1:1 Problems occurred with Green Mountain Reservoir including exhausting the historic users pool (HUP) and the impact of the Heeney slide, which prevented full use of the reservoir's available storage. 1:1 Denver Water reduced its by-pass flows past their Moffat Collection System, significantly reducing streamflows in the Fraser River Basin. 1:1 Due to agreements between water users and Excel Energy, there were changes in the administration of the Shoshone Call. 1:1 Clinton Reservoir may fail to fill for a fourth consecutive year, causing shortages in the planned 3-year supply for certain shareholders. 1:1 Denver Water has nearly exhausted its Williams Fork Reservoir supply and resorted to use of Dillon Reservoir to augment its Fraser River diversions. The degree to which these problems affect the published yields and shortages in the UPCO study are not certain. However, the participants agree that these issues should be considered during the next phase (Phase III) of the study and evaluated for potential impacts on the future shortages and water requirements of the water users in the basin. VI. Next Steps Phase II of the UPCO Study has identified a number of issues and problems that warrant further study. The objectives for the next phase need to be identified and the role and organization of UPCO needs to be defined. This may involve formation of one of more