Laserfiche WebLink
<br />GREEN RIVER STUDY PLAN <br /> <br />28 <br /> <br />February 2,2007 <br /> <br />Implementation <br /> <br />· New Start.- The study should begin as an evaluation of floodplain nursery habitat <br />availability and quality during the winter of 2007-2008 (FY 2008). Depending on the <br />availability of hatchery-reared fish and peak flows of sufficient magnitude to inundated <br />floodplain habitats, a study of habitat quality, survival of young-of-the-year razorback <br />suckers, and survival and movement of subadult razorback suckers into the main stem <br />river would be initiated and continued for three successive years. Assuming fish and <br />flows are available in the spring of 2008, the study would continue through 2011. A final <br />report would be prepared in the following year (2012). <br /> <br />2: Complete evaluation of recent peak flow studies related to floodplain <br />inundation and entrainment of larval razorback suckers, and determine the <br />need for additional studies. <br /> <br />Description <br /> <br />A three-year study of entrainment and floodplain inundation is in its third year, and a <br />fmal report is expected at the end of 2007. The results of this study should be evaluated to <br />determine if additional studies are needed. Among the issues that should be addressed by the <br />fmal report are the flows at which key floodplains with levee breaches become connected to the <br />mainstem and inundated, entrainment rates at different flows, levee breach configuration that <br />enhances larval entrainment, and the effect of river flows on associated channel geomorphology. <br /> <br />The magnitude and duration of spring flows necessary to optimize larval entrainment <br />under the full range of hydrologic conditions (e.g., wet, moderately wet, average, etc.) is an <br />outstanding information need. This includes, but is not limited to, the analysis of possibilities for <br />meeting the goals of the flow recommendations at various peak flows (including peak flows that <br />minimize spillway use and the risk of nonnative fish escapement from Flaming Gorge <br />Reservoir). The synthesis of these studies should be used to assess differences in floodplains that <br />translate to year-to-year variability in configuration and larval entrainment. Understanding <br />annual variability of floodplains will help to better understand timing and magnitude of dam <br />releases that most benefit the endangered fish. <br /> <br />Data collected on floodplain habitat connection and inundation (aerial photography, inlet <br />surveys), sediment deposition and erosion in floodplain habitats, and entrainment studies should <br />be integrated to determine how entrainment is affected by flow and physical characteristics of <br />floodplain habitats (Table 2; e.g., Western aerial photography, Cap 6 HYD physical evaluation <br />of floodplain habitat, 85f sediment monitoring, evaluation of ecosystem restoration and <br />management options for the Ouray NWR). The synthesis report will provide important <br />information to determine the effectiveness of existing flow recommendations, and identify <br />opportunities for refinement of flow management strategies to entrain larvae, provide sufficient <br />floodplain nursery habitat, and maintain floodplain habitats over the long-term. As necessary, <br />additional studies that address priority hypotheses and information needs should be planned for <br />subsequent years. <br />