9520 - Laserfiche WebLink

Home Browse Search

interpretations and lead to confusion. The study would have benefitted from current site specific curves. The greatest shortcoming was that the study design should have included seasonal flows and fish habitat use, not just base flows. Although a geomorphology study, "Geomorphic analysis in support of a channel maintenance flow recommendation for the White River near Watson, Utah," was conducted to address flood flow during spring runoff, the biology component was limited to the base flow period. Most of the results from this study were based on the wetted perimeter-discharge relation. The Instream Flow Council (2002) has admonished researchers to move away from the use anyone tool and toward the use of a suite of methods. Colorado pikeminnow Flow Requirements in the White River Despite the uncertainties and shortcomings above, we make the following comments on the flow requirements. Adult Colorado pikeminnow occupy the White River year-round. The fish undergo spawning migrations of hundreds of miles to sites in the Yampa and Green rivers. Typically, sexually mature fish migrate out the White River by mid-Mayor mid June and return by mid- to late August (Irving and Modde 2000). The downstream migration is thought to be cued by descending spring runoff flows and temperature(Tyus 1990, Modde and Smith 1995). Fish passage over shallow riffles is dependent on adequate flow, especially for the return trip in August. Maximum riffle production occurs during base flow period in summer and early autumn, which supports the prey of Colorado pikeminnow. Multiple flow levels are required to meet the needs of the White River Colorado pikeminnow. To cue the fish to migrate, a natural hydrograph is needed during spring runoff To provide for passage over riffles, flows >300 cfs are apparently needed. To maintain riffle 18