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r . ~ P g"Za ass/~ ~v°° ~ ,~ ` 29 Habitat Depth The biological assessment includes results of an analysis of effects on habitat depths caused by the Project's re ction of flows (Biological Assessment, Appendix 6, Tables 3.14 throw h 3.19 and Attachment G). This analysis was based on extrapolation of fl w/depth measurements taken in four study sites within the 15-mile reach as d scribed in Osmundson et al. (1995). The results show that reductions a itat the for all habitat types in the 15-mile reach would range f om 0 to 1 inch on average, during both-the summer and winter. The results i-fin i~ a at effects on habitat depth are ~''~"'~-- significant only during the summer (August through October) with most effects associated with backwater habitats. ~. Habitat Area 1, ~•~~~ '~~:, . s a The biological assessment also includes the results of an analysis of changes ~,,~~ in habitat areas caused by the Project's reduction of flows (Biological Assessment, Appendix B, Tables 3.20 and 3.21). This analysis was based on ~ ~ ~'' extrapolation of flow/area measurements taken in four study sites within the P ~"ZO 15-mile reach as described in Osmundson et al. (1995). Changes to habitat ~~ ~ areas were calculated in two ways. The calculations were first performed 6~c~(> assuming that the four study sites contain 66.8 percent of the total habitat h. " in the 15-mile reach; this assumption was based on the Service's finding that ~~ 66.8 percent of radio telemetered squawfish locations in the 15-mile reach occurred within the four study sites. These results show that the area of all habitat types would decrease in the 15-mile reach by 0.36 acre in the summer and 0.25 acre in the winter from a total of 84 acres and 96 acres respectively, and the area of preferred habitats would increase in the 15-mile reach by 0.02 acre in the summer and 0.40 acre in the winter from a total of 5.1 and 10.7 acres respectively. The calcul m assumin a linear relationship between a itat area in the four study sites n - ch. T e u s s ow a the area of al a itat types would decrease in the 15-mile reach by 1.2 acres in the summer and 1.1 acres ~_>~ in the winter from a total of 396 acres and 456 acres respectively, and the ~--~ 7 area of preferred habitats would increase in the 15-mile reach by 0.07 acres in the summer and 1.9 acres in the winter from a total of 24.3 acres and 50.8 acres respectively. ~ _ 5~Q ~,c ~~s~ r3 A z The analysis of changes in area of preferre s during summer as presented in the biological assessment is law The analysis evaluated the effects on habitat areas caused by the Pro~ec s reduction of flows from 814 cfs to 795 cfs. However, backwaters, eddies, and pools were mistakenly identified as the preferred habitats at these flows. Slow and fast runs are JG`,~ ~ the preferred habitats at these flows. According to the results of the analysis, the Project will decrease the area of slow and fast runs. Also, the extrapolation of measurements of habitat area in the four study ~: sites to the entire 15-mile reach assuming that the four study sites contain ~~~~'`~ x 66.8 percent of the total habitat area in the 15-mile reach (basemen t ems' `'"'~'~ Service's finding that 66.8 percent of squawfish radiot ons in the 15-mile reach occurred within the four study site s flawed. is not possible for the four study sites, which constitute 14 a length