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." :'\ ,. !It 1." Affected Environment & Consequences .... -'_'--' . u 3-31 fluctuations cannot be blamed for poor survival and recruitment of young-of-the-year rainbow trout to age 1+ for either 1994 or 1996 (Nehring, August 1997), After dividing 1985 through 1992 and 1993 through 1995 into "before" and "after" whirling disease (BWD and A WD, respectively), rainbow trout density and biomass experienced a significant decline in the A WD time period. There were no significant changes in the brown trout population parameters when the data set was divided into the same BWD and A WD time periods. It is unlikely that significant declines in age 1+ recruitment, density, and biomass of rainbow trout that began in 1992 in synchrony with the documented presence of M. cerebralis just upstream of the study reach in 1991 is coincidental; it is a result of whirling disease. The disappearance of wild rainbow trout fry is occurring across all types of water years, i.e., below average, average, and above average discharges (Nehring, August 1997), The CDOW believes that the AB Lateral will neither have positive nor negative impacts on occurrence of whirling disease in the trout population (Nehring, persnnal communication, Oct. 30, 1997), Impacts to the game and nongame fishery of the Gunnison River resulting from changes in water temperature seem unlikely, especially considering that the minimum post- development flows and maximum water temperatures would not differ substantially from the low flow conditions observed during 1977, 1981, and 1988, During these low flow years, trout populations remained healthy and viable. Another possible effect of lower winter flows, which would be a result of the proposed Project, would be that native species (flannelmouth and bluehead sucker) would move further upstream in the Gunnison River. Currently, these species do not usually move past the Gunnison's confluence with the North Fork. However, during recent low-flow years, the CDOW has observed upstream movement of these species (Sherman Hebein, CDOW, personal communication, 1997), The FEIS presented a lengthy discussion of the effects the proposed Project could have on trout habitat in the Gunnison River, The studies were conducted using the PHABSIM model combined with river data collected in the field. Results of those studies give an indication of availability of trout habitat at pre- and post-project flows. This is the result of the relationship between available habitat and river flow. Table 3-16 compares the average river flows for the No Action (Alternative A) and development alternatives (E-l through E-3) to the optimum flow conditions for various life stages of brown and rainbow trout. AS Lateral Hydropower Project July 2000 .,if