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<br />rf!)i)188 <br /> <br />Results of Additional Model Runs <br /> <br />December 2,2, 1993 <br />Page 2 <br /> <br />contract pools would benefit from a partial refill and would thus potentially be able to deliver <br />more than their contract amount in a single year, In reality, the Upper Yampa District would <br />probably go ahead and store this water rather than bypass it, Therefore, we have modified the <br />reservoir network structure to limit deliveries out of the contract pools to their contract <br />amounts, eg, power = 9,000 af per year, while additional water may actually be available in <br />the pools as a result of the refill, <br /> <br />We have also modified the hydropower operation at Stagecoach, This was originally <br />implemented as a winter evacuation of about 7 kaf (equivalent to 10' drawdown from full pool) <br />regardless of actual reservoir contents, While this worked OK for the current demand <br />scenario, it caused unrealistic drawdowns under the future demand scenarios and the <br />Environmental Baseline scenarios, At our meeting, John Fetcher said he wouldn't draft the <br />reservoir for power if it was already drawn down in the fall. The hydropower operations at <br />Stagecoach are currently implemented by defining a set of decreasing end-of-month storage <br />targets. Power releases are only made when the reservoir is still above target after making its <br />contract and environmental releases, The targets in the enclosed model runs .call for a total <br />drawdown of 10,000 af by the end of March each year, <br /> <br />The minimum "environmental release" modeled below Stagecoach is either 20 or 40 cfs, <br />depending on the season, or reservoir inflow; the 20 cfs is a hard minimum regardless of <br />inflow, Releases from Stagecoach to satisfy this requirement are not counted against the <br />annual storage decree limits if these releases are determined to be discretionary bypasses of <br />free water, Le" when they are made in months when there was not a call against Stagecoach, <br /> <br />Elkhead Reservoir <br /> <br />We model two decrees for the existing reservoir. <br /> <br />First decree - 5,389 af/year <br />Second decree - 8,310 af/year <br /> <br />There are no minimum releases or recreation pool constraints on the existing reservoir <br />and there is no release made for flow enhancement in occupied habitat (the 5000 af release), <br />These operations may be re-included in some form in the operations of the enlarged Elkhead, <br /> <br />The Craig Station is assumed to use Elkhead first for supplemental water, then <br />Stagecoach, The Wessels-based direct flow right for the Craig Station is assumed to be just <br />senior to the Wessels-based Bear Reservoir storage decree at Stagecoach, <br /> <br />Steamboat lake <br /> <br />We now model two decrees at Steamboat Lake, <br /> <br />First decree -23,064 af/year <br />Second decree - 3,311 af/year ("surcharge pool") <br /> <br />Releases from the 3,311 af pool are made only to the extent that there is water stored <br />above the emergency spillway, Le, reservoir contents are greater than 23,064 af, The release <br />occurs in September and October, <br /> <br />Hayden Station power demands not satisfied by direct flow are assumed to be served <br />first by Steamboat Lake, then by Stagecoach, <br /> <br />Hydrosphere Resource Consultants 1002 Walnut Suite 200 Boulder, Colorado 80302 <br />