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information is evaluated. Continued ongoing research and new information related to evaluation of the fish passageway will provide opportunity for refinement of the minimum streamflow recommendation for passage and year-round streamflows for habitat maintenance for all life stages of endangered fish in the 2.3-mile reach of the Lower Gunnison River. As additional studies related to evaluation of the fish passageway are completed, knowledge of the relationship between discharge and water depth versus fish habitat will continue to evolve. Channel morphology changes such as widening and aggradation of the channel may decrease the maximum water depth at present locations where water depth is now critical. If so, this may necessitate increasing the 300 cfs minimum flow recommendation. Results of completed hydrology studies as well as ongoing habitat and geomorphology studies in the Gunnison River drainage and downstream reaches in the Colorado River will be used to write a biological opinion on operation of the Aspinall Unit, as well to identify recovery actions appropriate for the Gunnison River to assist in recovery of endangered fishes. Refinements to the minimum flow recommendation for passage in the 2.3-mile reach will be made as additional biological and hydrological data become available. Passage flows and comprehensive year-round flow recommendations that will optimize habitat and provide for recovery of Colorado squawfish in the Gunnison River will be incorporated into the final Aspinall Unit Biological Opinion. RECOMMENDATIONS Recommendations for the 2.3-mile reach of the Lower Gunnison River include, 1. Continue to implement a year-round, instantaneous 300 cfs minimum flow using water releases from upstream Federal Reservoirs. The 300 cfs minimum flow is especially important to maintain during the summer low-flow period (July- September) so that endangered fish will have access to the fish passageway. 2.. Continue to obtain biological and hydrological data to evaluate the 300 cfs minimum flow for passage of sub-adult and adult Colorado squawfish. Continue to evaluate if a 1-foot water depth is sufficient for passing adult Colorado squawfish. During experimental low flows or during natural low-flow periods, measure water depths at critically shallow areas, correlate with known flows, and observe the response of both endangered and native fish in the reach. Based on these data, recommend a permanent minimum flow for passage. Utilize radiotagged Colorado squawfish to refine or validate the minimum passage flow recommendation. Delineate and quantify habitat- use data at various flows using aerial video and on-ground mapping. Compare above data to determine habitat preference for Colorado squawfish and identify and recommend year-round flows for maintaining and enhancing habitat for sub-adult and adult Colorado squawfish in the reach. These flows would be in addition to the minimum flow identified for passage and would be integrated into flow recommendations for the entire Gunnison River. 35