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<br />002~68 <br /> <br />Using these synthesized daily flows, the Service estimated gross daily deficits of summer (93 cfs) <br />and winter (124 cfs) flow targets (Figure 8). White bars in Figure 8 represent daily net deficits of <br />flow targets in historical context based on the difference between future average daily flows in cfs <br />and the lesser of 93 cfs or the corresponding historic daily average flows. Annual deficits were <br />calculated as the sum of daily deficits. Days with estimated future streamflows exceeding 93 cfs <br />did not offset days in which there were deficits. Annual net deficits were calculated by subtracting <br />historic gross deficits from future (or current) gross deficits (Table 15). Net deficits represent the <br />smallest augmentation volumes needed to precisely satisfy the flow targets in their historical context <br />and were used to quantify augmentation needs. <br /> <br /> 372 279 <br /> 310 248 <br /> > <br /> o Future net deficits (AF) < <br /> 248 217 III <br />-- ... <br />u.. Cl) o Historic surpluses/dt;lficits Dl <br />cS: E1 lC <br />-g 186 . Future (days wlo deficits) 186 CD <br />Gl Co <br />CI;t Dl l <br />.. 0 124 155 :: <br />~I;: '< <br />u 0 Co <br />III _ 62 124 iii' <br />:c Cl) n <br />>- .~ :::r <br />- - 0 93 Dl <br />.- ClI ... <br />ca_ '" ;n- O) lC <br />C E ... ;;;- iD 0;- 0;- 0;- CD <br /> e e ;;; N" <br /> (62) !::. !!. !!. N" 0) ;;; ;. !!!. !!!. !!. !!. 62 - <br /> 0) " e e n <br /> " - iiI' <br /> (124) ~ 31 - <br /> (186) 0 <br /> Days <br /> <br />Figure 8. Illustration of hypothetical daily deficits of fish flow targets <br /> <br />Net deficits under 2045 demand conditions ranged from zero during moderately wet to wet years <br />(:S30% exceedance), up to 9,689 AF in 1977, an extremely dry year (100% exceedance). For the <br />driest 10% (9 out of90 years) annual net deficits average 8,390 AF, whereas in 80 years annual net <br />deficits are less than 6,000 AF (Table 15). On this basis, the Service concluded that 6,000 AF, plus <br />an allowance for transit losses, would be sufficient to satisfy the base-flow recommendations for the <br />endangered fishes through 2045 in all but the driest years. This volume also would serve to reduce, <br />though not totally eliminate, net deficits in the driest years (Table 16). <br /> <br />To evaluate augmentation water supply alternatives, a subcommittee representing Yampa River <br />Basin water users, Upper Basin water users, the Colorado River Water Conservation District, <br />Colorado Water Conservation Board, Colorado Division of Water Resources, Service and The <br />Nature Conservancy adopted the 6,000-AF augmentation volume, and added 1,000 AF (16.67%) <br />to account for transit losses. <br /> <br />Management Plan for Endangered Fishes in the Yampa River Basin <br /> <br />34 <br />