Colorado's Plan for Future Depletions

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, Colorado's Plan For Future Depletions January 12, 1998 Documentation as Required by Cooperative Agreement, Page 8 Milestones W6-1, W7-1, W8-1, and Tab 3B(I)E _ monthly deliveries from Denver's Roberts Tunnel and Moffat Tunnel were obtained and used. It was assumed that Denver's use of these supplies would follow the same pattern as Denver's tunnel deliveries because most of Denver's transbasin diversions are used directly. Aurora's transbasin use was assumed to follow a typical municipal use pattern. While virtually all of Aurora's transbasin diversions occur during May through July, Aurora stores these diversions and then delivers them for municipal use on a year round basis. Municipal uses of Colorado-Big Thompson and Windy Gap diversions were assumed to occur in a monthly pattern that supplements the yield of native water supplies. Municipal use of these sources was therefore assumed to be relatively lower during the months of May and June and relatively higher during the months of July through September. 4.6.2 Nontributary GW - Use Pattern Municipal use of nontributary (Denver basin) groundwater was assumed to follow a typical Douglas County (South Region) municipal use pattern because nontributary groundwater is the primary supply for those municipal providers that rely on it. 4.6.3 Ag. Conversion - Use Pattern It is assumed that 80% of municipal use of converted agricultural water occurs during May through September, 10% in April and October and 10°lo in November through March. This pattern reflects the fact that conversion of agricultural water is primarily accomplished on a direct flow basis. 4.6.4 Conservation - Use Pattern It is assumed that conservation use would follow a municipal demand pattern typical of all three Regions because the water saved from conservation would be used to meet additional municipal demands on a year round basis. 4.6.5 Water Reuse - Use Pattern A campiled average monthly reuse pattern was developed from reported exchanges, direct reuse and augmentation activities by Denver, Aurora, Westminster, Thornton, Boulder and Douglas County users. Approximately 80% of reuse occurs during May through September clue to increased exchange and irrigation opportunities during this period. A non-uniform pattern was assumed during these months to reflect the fact that most exchange potential occurs in July and August when flows are still relatively high but downstream calls are on. Relatively less reuse occurs in May and June due to high natural stream flows and resulting ample yields from other water rights. The remaining 20% of reuse occurs during October through April and reflects augmentation of various junior nnunicipal rights including alluvial wells.