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1 t Summary results of CDM's habitat/depth evaluation are provided in Tables 3.14 through 3.19. Attachment G provides the detailed monthly results of the habitat depth evaluation. The summary tables provide average habitat depths over the 19-year simulation- period and habitat depths for representative low runoff (1977) and high runoff (1984) yeazs, under both current and future conditions for winter and summer months. Also shown are the percentages of time that habitat depths would have been greater than or equal to the preferred depth ranges identified by the USFWS. For all of the transects, the summary tables show that reductions in habitat depth for all habitat types due to future diversions by the District would have been relatively small, ranging from 0 to 1 inch, on average, during both the summer and winter seasons. A In terms of meeting the preferred depth criteria, Table 3.14 shows that backwater habitats would have virtually never met the criteria under both can ent and future conditions. However, Table 3.15 shows that at this same transect following spring floods (when the USFWS repeated its measure- I~ ments), the criteria would have been met more frequently during the summer and always during the winter, even after Ute's future diversions aze accounted for. The potential availability of backwater habitats may be more dependent on the frequency of flushing due to spring flooding than the effect of future diversions by entities such as the District. For eddies, pools, fast runs, and slow runs (Tables 3.16, 3.17, 3.18, and 3.19, respectively), suitable depth would have been typically available under both current and future conditions at least 50 percent of the time during the summer months and nearly always during the winter months. The results of this analysis indicate that river flow effects on endangered fish species habitats are generally only significant during the summer months (August through October), with most effects associated with backwater habitats. 3.3.6.2 Habitat Areas Another component of the USFWS (1995) study was the identification of habitat area within the four study sites of the 15-mile reach. The USFWS identified a total habitat area ranging from 211,993 square meters (52.4 acres) to 405,406 square meters (100.2 acres), depending on the streamflow level in the Colorado River at the time of the measurement. It should be remembered that these habitat areas are not the total available over the 15-mile reach, but only represent the habitat areas within the four USFWS study sites. These areas were further broken down by habitat type in the USFWS report, with values provided at 13 flow rates measured during the course of the study. During both the summer and winter months, the habitat areas (based on USFWS data) that would have been available under future District diversions were computed for the flow rates defined in this appendix. Table 3.20 presents the results of this evaluation. During the summer months, average flow rates at the top of the 15-mile reach would have been expected to decrease from 814 cfs to 795 cfs (19 cfs reduction) due to District diversions. Winter flows would have been expected to decrease from an average of 1712 cfs to 1688 cfs (24 cfs reduction). Using the flow/area values measured by the USFWS and provided in Table VIII of their report, available areas of each habitat type were computed for these average flow rates by interpolating CDM Camp Dresser & McKee o:~aoa~-i io~nocwPr~n-s.noc B-20