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<br />18 <br /> <br />Reach One Spring Peak Release Results <br /> <br />The estimated flows at all points along Reach One were assumed in the model results to <br />be the same as the release rate from Flaming Gorge Dam, During the spring, the model released <br />the volume of water necessary to safely operate the reservoir while also achieving the objectives <br />of the Action (ALL and ALL-I) and NoAction alternatives, Figure 13 shows the distribution of <br />the peak flows (greatest magnitude single day average flow) that occurred in Reach One for all <br />three model runs, The capacity of the power plant at Flaming Gorge is assumed to be 4600 cfs, <br />Releases greater than 4600 cfs are considered bypass releases, Figure 13 shows that water was <br />bypassed by the No Action model run in about 18% of all years, The Action (ALL-I) model run <br />bypassed water in about 37% of all years while the Action (ALL) model run bypassed water in <br />about 53% of all years, It is also noted that bypasses from the Action (ALL and ALL-I) model <br />runs had significantly higher magnitudes than those for the No Action model run, For reference, <br />historic peak flows for the period from 1971 to 1991 are included in Figure 13. This historic data <br />includes years 1983, 1984, and 1986, which were abnormally wet years in the Upper Green River <br />Basin. Statistically, it is very unlikely that three years of such high magnitude would occur <br />within 20 years of record. The historic record presented in Figure 13 is therefore statistically <br />skewed toward wet conditions, Figure 13 also shows that the differences in peak releases <br />between the Action (ALL) and the Action (ALL-I) model runs were significantly larger than the <br />differences between the Action(ALL-l) and No Action model runs, <br /> <br />FIGURE 13 Distribution of Peak Flows in Reach One <br /> <br />Flow Durations (May - July) <br />Reach 1 <br /> <br /> 14000 <br /> 12000 <br /> 10000 <br />~ 8000 <br />~ <br />~ <br />~ <br />l'i': 6000 <br /> 4000 <br /> 2000 <br /> <br /> I <br />-II- ~ No Action Peak Flow <br /> + Historic Peak Flow (71-91) <br /> -I- All - I Peak Flow <br /> I All Peak Flow <br /> .., <br />'J. [77" ., <br />-L- L -, -, <br /> " L- --, <br /> ., l <br /> n <br /> <br /><1>% <br /> <br />20% <br /> <br />40% 60% <br />Percent Exceeded <br /> <br />80% <br /> <br />100% <br />