ENVIRONMENTAL IMPACTS

Water Resources

There is no evidence indicating that existing winter recreation activities have an impact on water resources. It is unlikely that pollutants build up in concentrations large enough to cause a measurable impact on surface water quality. Use of snowmobiles and other mechanized snow machines is prohibited near the caldera rim and confined to the north entrance road. As a result, oil or other chemicals that may leak from the snow machines do not enter Crater Lake. Additionally, there are no surface water bodies in proximity to the north entrance road that would be contaminated by exhaust emissions or chemicals leaked from snow machines.

To protect water resources from backcountry skiing and camping activities, regulations require that all campsites be located at least 100 feet from any surface water body. Because winter use in the park will remain much as it is under existing conditions, it is unlikely that impacts on surface water resources would occur.

Wildlife

Crater Lake National Park is not heavily used by wildlife during the winter months, because many of the larger animals, such as deer and elk, migrate to lower elevations to escape deep snow conditions. Other animals hibernate during the winter season. The species that do live at higher elevations during the winter are minimally affected by existing winter activities. There is no evidence indicating that existing winter use activities in Crater Lake National Park adversely affect wildlife. Therefore, because use levels would not increase and areas of activity would not change significantly, no impacts on wildlife species are expected to occur.

Air Quality

Snowmobile and motor vehicle exhaust would continue and potentially increase proportional to increased snowmobile use and the number of motor vehicles entering the park. However, neither snowmobile nor vehicle traffic occurs in volumes great enough to cause notable impacts on air quality. It is unlikely that emissions would noticeably increase as a result of plan implementation. Air quality would remain within Class I area standards.

Soils and Vegetation

Implementation of the winter use plan would not cause impacts on soils or vegetation within the park. Soils are covered by several feet of snow during the winter season, and the winter use plan does not propose to develop any structures or facilities to support winter activities.

Snowmobiles are required to stay on roadway corridors used during the summer season; therefore, impacts on vegetation from snowmobile use are not expected to occur. In addition, backcountry fires are prohibited during the winter season to protect standing vegetation.

Threatened and Endangered Species

Implementation of the winter use plan would not have an impact on threatened or endangered species inhabiting Crater Lake National Park during the winter. A pair of peregrine falcons are known to nest west of Rim Village during the spring and summer months, and it is assumed that they hunt during the park's higher elevations throughout the entire year, although probably at a reduced level during the winter months, when the prey base is reduced. There is no indication that existing winter activities in the park adversely affect these species. Under the preferred alternative, active winter use in Crater Lake National Park will continue, for the most part, as it has in past years. No expanded winter recreation is proposed under the winter use plan, and the continuation of these activities will not affect threatened or endangered species.

Cultural Resources

As discussed, implementation of the winter use plan would not require construction of structures, roads, or other facilities to support winter recreation. Therefore, implementation of the winter use plan would not affect structures, landscapes, or road and trail segments of historical or cultural significance. Potential impacts on cultural resources caused by implementation of the Development Concept Plan (DCP) will be addressed in the environmental impact statement (EIS) that will be prepared for that project.

Noise

Snowmobile use generates the greatest amount of noise of any winter use activity occurring within the park. Snowmobile use will be confined to the existing route along the north entrance road; as a result, noise impacts resulting from plan implementation are not expected to increase. As discussed, it is the NPS's intent that the quiet and solitude of the winter backcountry experienced be preserved. Therefore, no additional mechanized equipment, such as trail groomers, will be permitted.

Recreation

Recreation impacts related to overnight camping in the Rim Village area would not occur, because this activity will be prohibited under the preferred alternative. The plan supports maintenance of existing recreational opportunities for snowmobiling, cross-country skiing, snowshoeing, and overnight camping.

Water Resources

Under Alternative 2, the potential for impacts on water resources would be less because the use of mechanized snow machines would not be permitted in the park, and backcountry use would be restricted to day use. While there is no evidence indicating that existing activities affect surface water resources, eliminating these uses from the park would reduce potential impacts.

Wildlife

There is no indication that existing winter activities in Crater Lake National Park adversely effect wildlife species. However, it is assumed that reduced winter use would have a positive effect on species inhabiting the north area of the park or the backcountry areas frequented by overnight campers.

Air Quality

Eliminating the use of mechanized snow machines in the park would eliminate snow machine exhaust emissions. Existing emissions do not generate a noticeable air quality impact in the park. If snowmobile use were eliminated, exhaust emissions related to these machines would be eliminated. Although this would likely not result in a noticeable change in air quality, short-term odors and irritants associated with snow machine exhaust would not occur.

Soils and Vegetation

No impacts on soil or vegetation occur during the winter season under existing conditions, because snowmobiles are required to stay on road corridors, and because campfires in the backcountry are prohibited. Reduced winter use would not have an impact on soils and vegetation.

Threatened and Endangered Species

While there is no evidence indicating that winter activities have an impact on threatened and endangered species in the park, reduced winter use would lessen impact potential. Eliminating snowmobiling and backcountry camping from the park would reduce noise and decrease human presence in the north entrance area and in the park's backcountry. It is assumed that the reduced potential for impact would benefit any threatened or endangered species in the area.

Cultural Resources

No cultural resources are affected by existing winter use. Reducing winter use would have no affect on the park's cultural resources.

Noise

Eliminating the use of snowmobiles in the park would reduce existing intermittent noise levels in the northern portion of the park. As discussed in the winter use plan, a major objective of the NPS is to preserve the quiet and solitude of the park's backcountry areas while providing access to all user groups.

Recreation

Under this alternative, winter recreation opportunities in Crater Lake National Park would be reduced. Snowmobiling and overnight backcountry camping would be eliminated. As data show, the number of visitors using backcountry areas during the winter is increasing. Eliminating overnight backcountry camping would have an impact on users visiting the park for this reason. In addition, eliminating snowmobile use would also have an impact on those visitors entering the park by snowmobile via the north entrance road.

Alternative 3 - Expanded Cross-Country Skiing

Water Resources

Impacts on water resources would be similar to those described for Alternative 1. The impacts on water resources (e.g., Annie Creek) from development in Mazama Village would be addressed in the EIS being prepared for the DCP.

Wildlife

Under this alternative, impacts on wildlife resources would be similar to those described for the winter use plan, with the exception that intermittent disturbances could occur in Mazama Village with expanded use of this area. It is unlikely that increased crosscountry skiing opportunities in the rim area would affect wildlife, because those few species active during the winter months are accustomed to intermittent human activity.

Air Quality

Impacts would be similar to those described for Alternative 1.

Soils and Vegetation

No impacts on soils and vegetation would occur under this alternative.

Threatened and Endangered Species

Impacts on threatened and endangered species would be similar to those described for Alternative 1. If Mazama Village were to be developed, impacts on threatened and endangered species in the Mazama area would be evaluated in the DCP EIS.

Cultural Resources

Impacts on cultural resources would be the same as those described for Alternative 1. However, if Mazama Village were to be developed, impacts on cultural resources in this area would be addressed in the DCP EIS.

Noise

Noise impacts associated with this alternative would be similar to those described for Alternative 1. It is not anticipated that noise impacts under this alternative would affect the quiet and solitude experienced in Crater Lake National Park's backcountry since crosscountry skiing is not an activity that generates a high level of noise.

Recreation

No impacts on recreation would occur under this alternative. Development of the Mazama Village area would increase recreation opportunities in the park. The presence of support facilities would further increase park visitation.

Water Resources

Increased use of mechanized snow machines in the park would increase the potential for impacts on water resources. An incremental increase in the release of pollutants such as petroleum products would be anticipated under this alternative. Use of snow machines and trail grooming equipment on the Pinnacles road would increase the potential for impacts on Wheeler Creek. Cross-country ski trail grooming equipment would also increase the potential for impacts downslope of groomed trail areas.

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.

Recreation

Recreation opportunities would increase for snowmobilers and cross-country skiers under this alternative. An additional snowmobile route along the Pinnacles road, along with groomed ski trails along portions of Rim Drive, would increase recreation opportunities for both user groups.

Mitigation

Implementation of the proposed winter use plan would not cause significant impacts on elements of either the built or natural environment. As described, impacts associated with implementation of the winter use plan alternatives would, in some cases, increase the potential for environmental impacts and an associated degradation in the winter backcountry experience. As discussed, environmental impacts associated with DCP development activities will be addressed in the EIS presently being prepared for the DCP.

No significant cumulative impacts from implementation of the winter use plan together with other actions such as the DCP are anticipated. Because this plan does not support or encourage new activities or increased use levels for existing activities, environmental issues associated with development of additional facilities will be evaluated in future documents.