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3.0 Scientific Basis And Underlying Principles 3-4 April 2004 Table 3-1. Recommendations for spring peak flows by hydrologic condition for Reach 2 (Yampa River to White River) to benefit endangered fishes in the Green River downstream of Flaming Gorge Dam (excerpted from Muth et al. 2000). Hydrologic Condition Criteria Wet Moderately Wet Average Moderately Dry Dry (0 to 10% (10 to 30% (30 to 70% (70 to 90% (90 to 100% Exceedence) Exceedence) Exceedence) Exceedence) Exceedence) General Peak flows in Reach 2 should be of the magnitude, timing, and duration to provide floodplain inundation in the Ouray recommendation portion of the river for at least 2 weeks in 4 of 10 years and at least bankfull flows in 1 of 2 years. In all years, peak flows should be of sufficient magnitude and duration to provide at least some in-channel habitat maintenance throughout the reach. No upper limits are placed on recommended peak flows in any hydrologic condition. The duration of peak flows less than 527 m3/s (18,600 cfs) should be limited, because neither floodplain nor backwater habitats are available at these flows. Peak-flow magnitude ~748 m3/s (26,400 ~575 m3/s (20,300 ~ 527 m3 Is (18,600 ~235 m3/s (8,300 cfs) cfs) cfs) cfs) in 1 of 2 average years; ~235 m3/s (8,300 cfs) in other average years Peak-flow duration Flows greater than Flows greater than 527 m3/s (18,600 cfs) Flows greater than Flows greater than 643 m3/s (22,700 cfs) 527 m3/s (18,600 cfs) should be maintained 235 m3/s (8,300 cfs) 235 m3/s (8,300 cfs) should be maintained should be maintained for at least 2 weeks should be maintained should be maintained for 2 weeks or more, for 2 weeks or more. in at least 1 of 4 for at least 1 week. for 2 days or more and flows greater average years. except in extremely than 527 m3/s dry years (~98% (18,600 cfs) for 4 exceedence ). weeks or more. Peak-flow timing Peak flows should coincide with peak and immediate post-peak spring flows in the Yampa River.