Laserfiche WebLink
streamflow variables (depth, velocity and substrate), 5) using hydraulic <br />simulation to determine depth and velocity combinations at unobserved <br />streamflows with respect to substrate conditions, and 6) calculating <br />weighted-useable-area (WUA) based on-the results from steps 4 and 5. <br />1. Species Distribution <br />The four rare fishes, historically located throughout much of the <br />upper and lower basins, have become restricted in distribution and <br />abundance because of obstructions to migration, changes in flow regime, <br />and other physical and biological factors (yIiller et al. 1982; Jones and <br />Tyus 1985; Tyus et al. 1987). In 1984 the FGVS Biological Subcommittee <br />con~leted a report to the UCRB Coordinating Committee identifying <br />"sensitive areas" of rare and endangered fish habitats in the Green, <br />Colorado, White and Yampa Rivers to protect the remaining riverine habitat <br />(Biological Subcommittee 1984).- Rivers were segmented and defined as <br />"sensitive" by any of these four criteria: 1) endangered species were <br />identified or collected in the reach, 2) the reach was used as a spawning <br />migration route, 3) the reach was confirmed or suspected as a spawning <br />area, or 4) the reach was considered a high density nursery area <br />(Biological Sub-Committee 1984). <br />Segment 3 within the Green River (FWS Segmentation Workshop, 8-12 <br />December 1986) was identified as a sensitive reach because it is a high <br />concentration area and a suspected spawning area for adult Colorado <br />squawfish, as well as a nursery and distribution area for young-of-year <br />and juvenile squawfish (Biological Subcommittee 1984; FGVS 1987; Table 1). <br />In addition it is a concentration area and suspected spawning area for <br />adult razorback suckers, as well as a low concentration area for adult <br />3 <br />