Wildlife
Wildlife impacts under this alternative would be similar to those described under Alternative 3. However, periodic short-term disturbance to wildlife could occur near Rim Drive when mechanized trail grooming equipment operates in this area.
Air Quality
Increased use of mechanized snow machines in the park for trail grooming and pleasure trips would increase overall emissions. However, it is difficult to predict whether emissions would cause a noticeable air quality impact. Cross-country skiers and other backcountry users may become more aware of snowmobile exhaust, thereby reducing the user experience for those winter activities. In addition, exhaust from mechanized trail groomers may impact cross-country skiers on East Rim Drive.
Soils and Vegetation
Impacts on soils and vegetation would be similar to those described for Alternative 1. Although activity in the park would likely increase, trail grooming and snowmobile use would occur in existing road corridors.
Threatened and Endangered -Species
Under this alternative, cross-country skiing and snowmobiling would increase around and southeast of the rim. During the winter months, peregrine falcon activity in the park is limited to perching, foraging, and occasional feeding on whatever avian prey is available. According to Johnsgard (1990), peregrine falcon prey includes rock and mourning doves, gray jays, waterfowl, and microtines (voles) during years of abundance. According to Follett (1979), only the gray jay is commonly present during the winter months. Although no data are available, peregrine falcon use of the park during the winter months is most likely low, with wintering activity primarily in the snow-free lowland areas outside the park where prey is in greater abundance (e.g., Klamath Lake).
Given the relatively minor increases in use that would occur under this alternative (groomed cross-country ski trails along portions of the rim and an additional 6 one-way miles of snowmobile trail), this alternative would not have a significant adverse impact on threatened or endangered species.
Cultural Resources
No impacts on cultural resources would occur under this alternative.
Noise
Noise impacts would increase with the use of mechanized snow machines along the Pinnacles road. Increased noise would disrupt the quiet and solitude of the existing Crater Lake backcountry experience. This impact would be inconsistent with Management Objective 4, which seeks to maintain the quiet and solitude of the backcountry areas by minimizing use of motorized, over-snow machines.
