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Section 5 Addressing the Water Supply Gap Technical Roundtable Implementation Issues: ~ Potential for increased compact call. ~ Additional in-basin storage. ~ Diminished flows in rivers below proposed diversions with potential increases in TDS and other water quality impacts. ~ Phosphorus levels in Dillon Reservoir. ~ Green Mountain Reservoir levels. ~ Green Mountain Reservoir/Wolcott Reservoir Swap. Potential Attributes: ~ Delivery to North Fork of South Platte upstream of Denver Metro area for gravity delivery to Denver Water customers and other water providers. ~ Protect or enhance Blue River flows. ~ Exchanges for additional flows in Colorado headwaters. ~ Multi-purpose storage for endangered species and other Colorado Basin needs. ~ Ability to exchange water for Summit County Municipal and Industrial purposes. ~ Recreation component for Wolcott Reservoir. 5.4.7 Yampa Pumpback The Yampa Pumpback Project would draw water from the Yampa River and transport it through an approximately 250-mile network of pipelines, pumps, and reservoirs to the Front Range. Figure 5-26 shows three pipeline alignments presented in the NCW CD 2006 reconnaissance study titled the "Multi-Basin Water Supply Investigation. " Water would be diverted from the Yampa River just north of Maybell. A 500,000 AF reservoir would be constructed to capture flows producing a firm yield of approximately 300,000 AF annually. Deliveries of 500 cubic feet per second (cfs) would be made to the Front Range through a single 108-inch diameter pipeline or paralle178 inch pipelines or a combination of the two. Where possible, the pipeline would be placed along existing easements, avoid wilderness areas and national parks, and minimize impacts in other areas through the use of tunnels. A 75,000 AF reservoir would be built along the Front Range northwest of Fort Collins, which would provide approximately 2 months of aqueduct delivery. Both West Slope and East Slope reservoirs would be constructed as earthfill dams. Approximately three pump stations with 60 AF reservoirs would be necessary to move water from west to east. Three hydropower stations may be included in the eastern segment. According to the report, the Yampa River at Maybell is of good water quality (TDS less than 300 mg/L) and would likely not require treatment levels exceeding conventional treatment. Preliminary analysis in the study concluded that the diversion of 300,000 AF of firm yield annually could be operated in such a manner to avoid potential constraints imposed by the Colorado River Compact obligations and Endangered Species Act (ESA) compliance on the Yampa and Green River. Additional environmental documentation would be required to ensure fulfillment of ESA requirements as well as assess environmental and recreational impacts. A major rafting reach and endangered species are downstream of the proposed diversion. A preliminary project schedule proposes construction of the reservoirs followed by the other necessary components beginning in March 2019. According to this schedule, water supplies could be online by May 2023. 5-40 FINAL DRAFT