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<br />5.4.3 Tia Juana Bottom <br /> <br />The calibration field data collection at Tia Juana Bottom took place during <br />July and August 1987, when a series of controlled releases were being made <br />from Flaming Gorge. Starting on July 6, 1987, a beginning release of 2,100 <br />cfs was established. This release was held constant, allowing flows at <br />Jensen, Utah to stabilize and only vary 100-200 cfs depending upon the flow of <br />the Yampa River. In successive weeks, releases from the dam were decreased to <br />1,800, 1,500, 1,300, 1,000, and 800 cfs. In mid-August, peaking power <br />releases were resumed with a varying release pattern of 800 to 2,600 cfs. <br /> <br />Model calibration at Tia Juana Bottom continued until the timing of peaks <br />aligned to within 1 to 2 hours, and simulated and recorded flows tended to <br />follow the same general pattern. Simulated flows matched recorded flows <br />within 5.6 percent over a 72 hour period. The pattern of simulated and <br />recorded flow was compared for the same 72 hour period and correlation <br />statistics were prepared. An "r" value of .99 was calculated for the Tia <br />Juana Bottom location which demonstrated that model timing parameters are <br />excellent and little further improvement could be achieved. <br /> <br />With Flaming Gorge peaking at 3,000 cfs from. a base flow of 800 cfs, travel <br />time to Tia Juana Bottom was 77 hours and changed the stage by .26 feet. <br />Peaking at 4,200 from a base flow of 800 cfs, travel time was shortened to 73 <br />hours and the stage was increased by .60 feet. Calibration results were based <br />upon a single flow event (release from Flaming Gorge Reservoir) which was <br />observed and measured at each recorder location for a period of 72 hours. <br />Figure 5-8 displays graphically the results of the calibration process at Tia <br />Juana Bottom. The information discussed above is also displayed in Tables 5-1 <br />and 5-2. <br /> <br />5.5 Future Uses of the Model. <br /> <br />Future uses of the SSARR model to save field testing appear to be great; <br />recently Western requested that the Service and Reclamation evaluate options <br />for spinning reserve releases (short duration high volume releases to cover <br />emergency outages on the system) from Flaming Gorge. The SSARR model was used <br />to simulate and evaluate the impacts of short term generation in excess of the <br />2,600 cfs interim flow requirements for August and September. The simulation <br />routed dam releases down to Tia Juana Bottom. . <br /> <br />Western is interested in evaluating the effect of spinning reserve releases <br />falling within the period the reservoir is being operate to provide stable <br />flows to enhance survival of larval squawfish. Western has estimated that the <br />provision of flows for endangered fish has resulted in a loss of 50 MWs of <br />generation capacity at Flaming Gorge. The resulting economic impact could be <br />substantially reduced if the 50 MW can be used for short periods. Preliminary <br />examination of this operation indicates the higher releases for several hours <br />did not substantially affect endangered fish habitat. In order to further <br />explore this option, Western requested that the tests described below be <br />performed. The data gathered will be used to further Westerns research and <br />are provided hear as an example of the type of analysis which can be performed <br />using the SSARR model as described in this Report. Other proposals from <br />Western will be analyzed using SSARR as a part of the Opinion. <br /> <br />5-5 <br />