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Asp.:. Highlands Ski Area - Draft E.viroN7lelllal Impat:l Slalemelll ENVIRONMENTAL CONSEQUENCES Since Steeplechase is the most frequently skied area with a potential risk of avalanches, it would continue to represent the main avalanche hazard under the No Action Alternative. In addition, pans of the Temerity area currently being skied are at times also affected by avalanches. However, neither of these areas, nor any others outside of the existing terrain, are to be further developed under the No Action Alternative; therefore, avalanche hazards would remain the same as at present. In the Steeplechase area, new terrain proposed by Alternative B that crosses gullies, which represent the track of avalanche staning zones with maximum runouts reaching the base of the drainage, could be affected by avalanches. Avalanches originating in Kessler's Bowl, South Castle Bowl, and Sodbuster Gully could affect several Steeplechase illt towers. Tbe Steeplechase Catwalk would cross the lower track and runout of several staning zones which could cause its closure during high avalanche risk periods. Avalanche activity in the Temerity area occurs infrequently, however, glading that would join small staning zones would increase the avalancbe risk. Due to their large open bowl configuration and less steep staning zones on the intervening ridge, the Highland and Maroon bowls represent significant avalanche hazards. This creates significant safety risks for avalanche conlrol teams crossing the bowls to reach their lower lift terminals at the opposite ends of the bowls. The lower Highland Bowl Lift terminal and associated catwalk could be affected by major avalanche activity originating in the upper portions of the bowl. Most of the Maroon Bowl Lift towers could be heavily affected by avalancbe hazards especially where the lift line crosses the narrower lower section of the bowl. Tbe Loge Bowl Catwalk could also be affected by occasional fairly large avalanches. The avalanche risk under Alternative C would be similar to that under Alternative B except that Maroon Bowl would be excluded. Neither the proposed Highland nor Ridge surface lifts would be affected by significant avalanche paths and would improve access to the avalanche staning zones between Loge Peak and Highland Peak that affect both Highland and Maroon bowls. Under this alternative, the Steeplechase Catwalk would be excluded and would not be subject to avalanche hazards but the Temerity Catwalk would be an additional element that might be affected by several small avalanche paths. POTENTIAL MITIGATION MEASURES Measures to mitigate the avalanche hazards in the expansion areas under alternatives B and C would include completion of an avalanche control plan prior to the development of any proposed new terrain. To prevent an increase in avalanche potential, the following tree thinning guidelines would be adopted: slopes <50 percent, unlimited thinning; 50-58 percent, <20 percent thinning; 58-62 percent, <10 percent thinning; and >62 percent, no thinning; and in the vicinity of staning zones, tree thinning should be perpendicular to fall lines. A surface lift from Loge Peak to Highlands Peak (that is longer than the Ridge Surface Uft), should be installed to attract more skiers to the ridgeline, thereby increasing skier compaction in the avalanche staning zones along the ridgeIine above Highland and Maroon bowls, and facilitating access by avalanche control teams. To reduce the avalanche hazard, particularly in Highland Bowl and Maroon Bowl, the following combination of techniques should be used: 1) pre-season boot compaction in avalanche staning zones; 2) delivery of air blast detonations to the upper portions of the bowls to prevent large overhead releases; 3) use of military anillery, an A valauncber or LOCAT device, to test snowpack stability in the upper bowl from a safe distance; and 4) placement of hand charges in the center portion of the bowl after the preceding measures have been taken. SOCIOECONOMICS AFFECTED ENVIRONMENT Most socioeconomic changes in Pitkin County have been associated with population growth, the local economy, housing, and community services, which together determine the quality of life in the area. While planned growth resulted in a 2.0 percent resident population growth in the 1980's, growth increased to about 3.4 percent during 28 Section III SOC;CH:conomics