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Infonnation from this table is displayed later in the Plan in reference to the streamflow goals. -..... Appendix A contains twenty figures that show historic mean daily outflow from Eleven Mile and Cheesman reservoirs~ Figures AI--AIO display Eleven Mile Reservoir mean daily outflow for each year from 1987 through 1996~ Figures AIl-A20 display Cheesman Reservoir mean daily outflow from 1987 through 1996. If you1re not yet tired of looking at historic data hydrographs, Figures 5-8 are streamflow duration curves of mean daily outflow for Eleven Mile and Cheesman reservoirs for the Aprill through July 31 and August 1 through March 31 periods. The figures show the following conditions: native streamflow 1947-1991 historic streamflow 1947-1991 historic streamflow 1947-1996 historic streamflow 1985-1996 Also shown on the figures are the minimum, maximum, and optimum streamflow goals that are described later in the Plan. Figures 5--8 illustrate two facts about how water supply facilities affect South Platte streamflow. First, the naturally occurring low flows in winter are boosted by storage releases from reservoirs. Second, the naturally occuning high flows in spring and early summer are reduced by reservoirs capturing the water~ These two characteristics of reservoir operations create tailwater conditions for high-quality trout populations in the ri ver. Figure 8 shows the peak mean daily inflows to Cheesman Reservoir that occurred each year from 1976 through 19964 As shown, these peak streamflows occurred as early as April and as late as August~ The majority of peak streamflows occurred in June. Figure 9 shows the South Platte River streamflows routed from Spinney Mountain Reservoir to Cheesman Reservoir for June 1 to July 31, 1997~ This figure shows how Eleven Mile Reservoir reduces peaks and fluctuations in streamflOW4 As shown, the inflow to Eleven Mile Reservoir fluctuates more widely than does the outflow. 4. Water Facilities The degree of streamflow management proposed in this Plan is based upon the utilization of native South Platte Basin streamflows, existing Upper South Platte Basin storage facilities, and existing and near-term importations into the Upper South Platte Basin. The primary source of water for municipalities along the Front Range is from melting snow in the mountains. A limited "window of opportunity~' from May to early July exists each year in which to capture enough water from the melting snow to maintain an adequate supply for the entire year. During the rest of the year, natural streamflow is generally inadequate to meet municipal needs. Snowmelt captured in reservoirs is also N:\Supply\ Waage\wildscen\attachb.doc B-25