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0025;)9 Biological Resource Impacts On November 6, 1997 the Arizona Oame and Fish Department (AOFD) surveyed cobble bars in the Lee's Ferry reach to assess rainbow trout stranding post downramp. AOFD evaluated stranding by dividing each cobble bar examined into quadrants and obtaining a total count of stranded fish by examining total area of the bars. AOFD also noted stranding of macroinvertebrates. Cobble bars selected for evaluation were representative of this habitat type in the Lees Ferry reach and were in areas which receive preferential use by fishing guides and fishermen. Observations: At RM -14, no stranding of rainbow trout and no apparent stranding of Garnrnarus lacustris or other macro invertebrates was observed. At RM -12.8, one dead rainbow trout (60mm) was observed to have been stranded and low concentrations of Garnrnarus were observed stranded in a few shallow pools, no other stranded macroinvertebrates noted. At RM -8, two live rainbow trout (90 mm and 400 -500 mm) were observed stranded in a large pool, Garnrnarus (Ll,OOO) of diverse size range were observed stranded in one small pool, and several thousand snails (physidae) were observed stranded on two small sand habitats associated with sedges nearshore. At RM -2.5, one dead adult flannelmouth sucker (Catostornus latipinnis) was observed in approximately 3 ft of water just inside mouth of backwater. This was judged not to be a stranding-related mortality. fl"j\-':') Concern over endangered species, particularly endangered Kanab ambersnai , prompted development of a U.S. Fish and Wildlife Service Biological Opinion on this federal action. A 2-3 October 1997 habitat and population survey at Vaseys Paradise revealed that 29.8 m2 of potential KAS habitat lay downslope from the 934 m3/s (33,000 cfs) flood stage. Five habitat patches were predicted to be inundated and potentially scoured. by the planned November Test Flow, but it was considered unlikely that the inundated vegetation would be completely eliminated. The habitat in the flood zone was estimated to support approximately 181 KAS (<1 % of the estimated total population). Immediately prior to the November Test Flow, the Arizona Oame and Fish Department salvaged habitat and 14 KAS from the inundated zone and is presently holding that material at the Phoenix Zoo. A OCMRC survey crew reported new sand and driftwood on the inundated habitat patches immediately following the event. Although losing 14.4% of the flood zone habitat to scour, the Test Flow did not completely eliminate vegetation in the habitat patches of concern. No impacts were anticipated or observed on " endangered southwestern willow flycatcher habitat. Impacts on endangered humpback chub were not considered to be detectable, and hence no effort was made to monitor that species. Conclusions These preliminary results indicate that top-of-powerplant flows can be used to rebuild low-lying sand bar platforms, and result in little disruption of terrestrial endangered species. A flow of this magnitude is probably insufficient to create or substantially rejuvenate backwater habitats, which serve as nursery habitats for native and non-native fish. Although some sand bars increased in area and volume, this flow may not have been of sufficient duration to maximize sand bar rebuilding. [January 14, 1998]