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""~,~,,,>,,.. ii' 'i l'''''''' ::l '_'..., ..~O'!V gallons (4.6 acre feet) would be necessary for the Dist~ct to be able to meet its needs and supplysnowrnaking water. spawning and overwintering habitat for brook trout are limiting in Snowrnass Creek. Snowrnakingwithdrawals could reduce brown trout overwintering habitat by greater than 25 percent (a threshold for significant impacts used by the Bureau of Reclamation) for two weeks in Alternatives F and G and for three weeks in Alternative E during a one-in-ten dry year. Brown trout riffle and spawning habitat (used as a surrogate for egg incubation habitat) would not be significantly affected. Brook trout spawning habitat reductions are predicted to reach the significance threshold during a one-in-ten dry year for two weeks in Alternatives Fand G and for five weeks in Alternative E. Flow reductions during a single year may not show measurable effects on the aquatic ecosystem, but recurring annual impacts may have a cumulative adverse effect. B. WILDLIFE AND BIOLOGICAL DIVERSITY 1. Affected Environment wildlife occurring within the project area and landscape assessment area are representative of habitats present in the Roaring Fork River Valley and are typical of wildlife associations in the central Rocky Mountain valleys of Colorado. No unus1,1al or rare species or groupings of species are known to exist within the project' area (PA) or landscape assessment area (LA). There are no federally-listed threatened plant or animal species that are known to occur within the PA. Federally-listed endangered species that potentially occur on the LA include: the Colorado squawfish, Humpback chub, bonytail chub, razorback sucker, bald eagle, Mexican spotted owl and peregrine falcon. There are no known federally-listed endangered plants, mammals, reptiles or amphibians within Pitkin County. Lifecycle and other biological information is provided and potential effects to listed species are evaluated in a separate Biological Opinion prepared by the u.s. Fish and Wildlife service (USFWS) on file at the Forest supervisor's Office and included in the project Analysis File. Except for the western boreal toad and northern goshawk, Federal Category 2 candidate species have not been reported to occur and suitable habitat is not present in the LA or PA. Bier Game Elk, mule deer, black bear, and bighorn sheep are the big game species of primary concern within the: PA. Elk and deer are the most abundant, although black bear are regularly seen in the area. The size of the MB-SW elk herd is estimated at 340 animals. Bighorn sheep are year-round residents of the southern portions of the PA. Calving habitat may be the most limiting habitat for the elk herd during mild to average winters. 'Historically, elk calving occurred within a 5,700 acre area between the Tiehack Ski Area and the western side of the Snowrnass Ski Area. Development in both of these areas has reduced elk calving to the lower portions of Burnt Mountain and adjacent private lands to the east. Ski area and private land development has resulted in an overall loss of approximately 3,100 acres (54%-) of the calving habitat that waS available prior to development. All indications suggest that as private lands are developed, habitats on NFSL will become incre~singly critical for elk calving. ' A herd of approximately 40 to 50 elk summers on the eastern edge of the permit area and adjacent private lands. This herd uses the upper portions of the calving habitat and adjacent conifer habitats throughout the summer months. Another herd of sPout the same size summers in the West willow drainage and surrounding area. Approximately l50 to 200 elk summer in the upper reaches of Main willow Creek and adjacent drainages, after migrating through the corridor Summary . 15