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Section 5 Addressing the Water Supply Gap Technical Roundtable A Blue River Pumpback could result in a significant number of benefits to the West Slope and ameliorate a number of West Slope problems, as described below. The following list is intended to be illustrative and may not be exhaustive. ~ Grand County Streamflow Management. Grand County bas experienced problems with low stream flows in the Upper Fraser and its tributaries and in the Colorado River below Windy Gap and is undertaking the development of a streamflow management plan to address streamflow needs. Related to these streamflow issues, a consortium of Grand County interests is purchasing shares in the Vail Ditch, which, with Denver Water's help and cooperation, could be wheeled to different points in the Upper Fraser. Additionally, a secondary benefit of a Green Mountain Pumpback could be a reduction in Denver Water's needs for substitution water from Williams Fork Reservoir and Wolford Reservoir, creating a possible source of storage water in Grand County for other uses, including stream flow enhancement. ~ Additional Grand Valley Water Supplies. Grand Valley entities have expressed a desire for additional water supplies for Green Mountain Reservoir Historic User Pool (HUP) entities and the "Slot Group," which includes entities outside Grand Valley. Fundamental to a Blue River Pumpback is the use of a portion of storage in Green Mountain Reservoir for the pumpback and the development of Wolcott Reservoir to replace Green Mountain storage. A Wolcott Reservoir might be sized larger to accommodate the Grand Valley's needs for additional water. ~ Dillon Reservoir Levels. Summit County wants to maintain higher Dillon Reservoir levels during the summer recreation season. Water pumped back to Dillon Reservoir after Dillon fills and spills could be held there during the recreation season, thereby improving reservoir levels, and then delivered to the East Slope after the recreation season. In years in which Dillon Reservoir doesn't fill, the pumped water could improve water levels during the entire recreation season. Additional W ater Supplies for the Upper Blue River. Water from the Pumpback could be exchanged for diversions by municipal and industrial users upstream of Dillon Reservoir or released from Dillon Reservoir for municipal and industrial users below Dillon. ~ Additional yield for Clinton Reservoir. Parties to the Clinton Reservoir Agreement have expressed a need for additional yield from the reservoir. Water from the pumpback could be used to provide a firm annual yield equal to the physical capacity of Clinton Reservoir. In addition to this increased yield in Summit County, a portion of the increased yield could be exchanged by Denver Water, using its facilities, for additional bypass flows in the headwaters of the Fraser River for West Slope use. ~ Blue River Flow Ei~llancement. Summit County bas identified an interest to improve stream flows in the Blue River below Dillon Reservoir. Yield from a Pumpback could be utilized for this purpose. ~ Additional West Slope Supplies. In the study, Wolcott Reservoir was sized to meet 20,000 AF of unspecified, future West Slope water demands. As mentioned above, Wolcott Reservoir could be sized to accommodate other West Slope needs. In addition to additional HUP and Slot Group demands Wolcott Reservoir could be sized to provide some or all of the 10,825 AF of water supply that the West Slope and East Slope have committed to provide to the 15-Mile Reach to aid recovery of endangered fish species. Wolcott Reservoir could also be sized to maintain a recreation or conservation pool. ~ Abandonment of Eagle River Rights. The East Slope use of the Blue River Pumpback could be an alternative for the East Slope's remaining conditional water rights in the Eagle River basin other than rights used to develop the Wolcott Reservoir. 5-38 FINAL DRAFT