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<br />Appendix A <br /> <br />Hydrosphere Resource Consultants, 1002 Walnut Suite 200, Boulder, CO 80302 <br /> <br />2 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />. The Flow Rec. - Junior - No Runoff Aug. scenario, which simulates the same operation as <br />the Flow Rec. - Junior scenario except that no storage releases are made for flow <br />augmentation during the months of April, May and June. <br /> <br />. The CWCB - Junior - No Runoff Aug. scenario, which simulates the same operation as <br />the CWCB - Junior scenario except that no storage releases are made for flow <br />augmentation during the months of April, May and June. <br /> <br />Key Model Assumptions <br /> <br />The Phase I and Phase II study scenarios were run using a monthly time step over the period <br />1930 -1982. Model scenarios run during the subsequent O&M studies used an extended <br />1930-1994 study period. <br /> <br />Modeled water demands in the Phase I and Phase II study scenarios were set at a projected <br />year 2040 demand level, which represents approximately 49,000 af of additional depletion <br />over 1989 levels (considered "current actual conditions" at the time of the Phase I study). <br /> <br />Modeled water demands in O&M Study scenarios were set at the level of the CWCB's <br />52,000 af development carve-out. All modeled demands were configured and/or relocated so <br />as to have access to contract storage in either Elkhead, Stagecoach, or Steamboat Lake <br />(Hayden Station only); this was done to insure that the full demand level or development <br />carve-out would be used to deplete the river. In reality, accomplishing this level of depletion <br />would require some small local storage development, use of pumps and pipelines, etc., to <br />meet tributary demands. <br /> <br />In all six scenarios, in-basin water demands were represented as diverting under their existing <br />or assumed future water right priorities. <br /> <br />In all six scenarios we assumed the enlargement of Elkhead Reservoir. In the Phase I Study, <br />the enlargement was assumed to provide a total capacity of 46,500 af. Based on better site <br />information obtained during later analyses, the Phase II and O&M studies assumed the <br />enlarged Elkhead capacity to be 44,900 af. <br /> <br />In the Phase I Study, Stagecoach Reservoir was also assumed to be enlarged, to a capacity of <br />52,000 af. This Stagecoach enlargement was not represented in the other scenarios. <br /> <br />In all studies the dead storage of the enlarged Elkhead was assumed to be 3,722 af. The <br />active capacity of the reservoir was divided into various pools operated for different <br />purposes. In general, these included municipal and industrial contract pools and an <br />"enlargement" or "augmentation" pool. In the Phase I Study, releases were made from the <br />enlargement pool to meet current and future in-basin demands not adequately covered by <br />existing storage contracts. In the Phase II and O&M studies,releases for in-basin demands <br />were made only from the contract pools while instream flow support releases were made <br />from the augmentation pool. <br />