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I I I I I I I I I I I I I I I I I I I Chapter 1: South Platte Basin Inventory March 21,1998 Page 1-13 assuming typical monthly CBT delivery patterns and stream depletion factors. The resulting monthly pattern was then added to the Kersey gage flows for water years 1950, 1951 and 1952, Chances In District 2 Diversions, For the period of October through March, it was assumed that changes in flow at Henderson and from the Cache La Poudre, Big Thompson and St. Vrain basins would be transmitted completely to the Kersey gage. For the period of April through September, it was assumed that a portion of the flow increases would be diverted by the irrigation ditches on the South Platte between Henderson and Kersey. The maximum demand of these ditches at Henderson was assumed to be 550 cfs based on previous call analyses done by Denver Water, Spronk and Hydrosphere. Any flow increase at Henderson in excess of this intervening irrigation demand was assumed to arrive at the Kersey gage. Estimated future flows for the Kersey gage are shown in Table 1-15 and Figure 1-15, 1.1.5 Reusable Flows Reusable flows from the metro Denver area were estimated only for the Henderson gage since most reusable return flows are generated at the Metro Wastewater Reclamation District plant or at downstream locations. All metro Denver area reusable flows are assumed to accrue to the river at the Henderson gage even though a small portion of these reusable flows would actually occur slightly downstream. Reusable return flows were estimated for both existing and future conditions. Estimates were generated as part of the MWSI project through review of existing and future water supply system operations for Denver Water, Aurora, Westminster, Arvada, Thornton, major Douglas and Arapaho County water districts, Broomfield, Northglenn, Englewood and South Adams County Water & Sanitation District. Reusable flows are discussed in more detail in Chapter 3. Estimates of existing and future reusable effluent are shown in Table 1-16 and Figure 1-16. The second graph in Figure 1-16 shows remaining reusable flows compared to total stream flows Henderson after accounting for reusable flows utilized in existing and future reuse plans. Additional reusable flows accruing to the river at the Kersey gage and not accounted for at the Henderson gage as discussed above consist of Windy Gap return flows plus net reusable credits resulting from irrigation rights changed to municipal uses in the St. Vrain, Big Thompson and Cache La Poudre basins. Currently there is relatively little Windy Gap water being used. The net reusable credits from Windy Gap use and changed irrigation rights is estimated to be approximately 5,000 acre-feet per Hydrosphere Resource Consu~ants, 1002 Walnut Su~e 200, Boulder, CO 80302