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nCi?1n Record of DecisIOn Landfonn and geologic conditions found in the area have slope stability conditions that should be factored into design and construction, but there are few areas of actual geologic hazards. Hazard areas that would be affected are primarily the undercutting of the dip slope plane along the Steeplechase catwalk and lift line, and areas atop or adjacent to areas of horizontal spreading (Sackungs). Natural events that might occur over the long tenn could impact facilities that would be constructed, therefore I have also required that construction plans for excavation include a detailed survey and design, and geo-technical evaluation by an independent consultant. HYDROLOGY $I What will be the effect to water quality, quantity, timing of flow and stream channel stability? The EIS indicated that with proper mitigation impacts to water resources could be maintained within acceptable levels under all alternatives. I have included several required mitigation measures to further reduce impacts. Among these is the requirement that most construction would occur without grading and stump removal. This will substantially reduce the amount of disturbed soils and the opportunity for increased sedimentation. This ROD requires that much attention be given in design and construction of facilities, such as the Deep Steeplechase catwalk. In addition, there will be nO ground disturbing activities until such time as a drainage/run-off control plan and schedule implementation has been reviewed and approved by the Aspen District Ranger. Impacts due to snowmaking include depletion of low winter flows in Maroon Creek and potential increases in snowmelt runoff and associated hillslope erosion. I have included mitigation requirements that will reduce these adverse impacts. ASC will be responsible for supplying daily logs of the water amounts used for snowmaking to ensure that snowmaking water withdrawals do not jeopardize CWCB's instream flow right of 14 cfs. ASC will also be responsible for proper implementation of best management practices (BMPs) contained in this document which are targeted at reducing erosion and sedimentation from runoff. AIR QUALITY $I How would development of the Aspen Highlands Ski Area affect air quality, both within Aspen's non-attainment area and the surrounding wilderness acres? Air quality could be affected with the removal of trees and the construction of facilities, as well as by the addition of traffic that might result from off-peak growth in skier visitations (shoulder seasons). The City of Aspen is in a non-attainment area under the Federal Clean Air Act, and a series of measures have been undertaken to bring the area into attainment. Additional measures are planned and are yet to be implemented by local government and others to reduce emissions and remain within confonnity of the State Implementation Plan (SIP). The analysis in the EIS notes that due to the insignificant increase in SAOT's, and a reduction from previous pernlitted numbers, the air quality will not surpass the PMIO daily threshold. The EIS included a conservative analysis of the potential air quality impacts of growth in shoulder-season skier visitations. This analysis concluded that impacts to regional air quality attributable to development of the Aspen Highlands Ski Area would be relatively minor especially in comparison to those occurring as a result of general growth in the area's population and increases in overall traffic volumes. Finally, the analysis indicated that wilderness air quality-related values could be adequately protected. This is currently the case based on the Forest Service air visibility monitoring site on Aspen mountain. Consideration of Environmental Issues Air Qualify 29