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o(jnfl~ S"""""", that about 285 lunch-time diners would use the restaurant each day and possibly hike in the vicinity of, and down from, the restaurant. POTENTIAL MITIGATION MEASURES In order to limit the number of skiers on Aspen Highlands to 3,480 SAOT, an electronic ticketLing system will be installed to monitor the number of skiers accessing the mountain, a local radio station will inform arriving visitors if the Aspen Highlands parking area is near capacity, and the delivery capacity of initial access lifts and ground transponation servicing the base area could be reduced. Since sununer use of Aspen Highlands is currently very limited. sununer activities proposed under Alternative C would not impact current activities, and no mitigation measures are proposed. HUMAN HEALTH AND SAFETY. AVALANCHE CONTROL AFFECTED ENVIRONMENT Aspen Highlands includes steep-sided. avalanche-prone terrain. The continental snow climate experienced in Pitkin County is characterized by cold temperatures and low density snow, which generally result in unstable snowpack. Timing of avalanche activity is often difficult to predict due to persistent deep slab instability. Steeplechase, Highland Bowl, and Marooo Bowl are the main areas of concern for avalanche control. The Steeplechase area is a wide, easterly facing slope that descends from Loge Peak and the ridgeline to the oorth down to Castle Creek. Individual staning zones and tracks are dermed by stands of timber. In some cases, connecting open spaces may result in two or more small to moderate-sized staning zones releasing simultaneously. While the Steeplechase area presents significant avalanche hazards, the smaller avalanche staning zones and numerous widely distributed "islands of safety" greatly facilitate avalanche management. Highland Bowl is a steep, primarily east-facing drainage. The upper slopes are steep enough (high 30 to lower 40 degrees) for frequent avalanche activity, but not so steep as to prevent a significant accumulation of snow. Thus. avalanche frequency and magnitude varies annually. The release of major ponions of the bowl with avalanche runs to the Sleepy Hollow or mid-track area at 10,000 feet tends to occur once in 3 years. Avalanches that run full-track, where at least a ponion of the debris reaches the valley floor in the vicinity of Castle Creek (at approximately 8,500 feet), may occur as often as once in 10 years. Evidence from tree growth and species distributioo patterns indicate that major avalanche events, which affect vinually all of the avalanche path and which produce large debris deposits on the valley floor, may have a return interval of once in 80 years. Smaller avalanches that could be dangerous or fatal to skiers would be very common. They could occur during any storm where a minimum of 6 inches of snow, accompanied by wind, would be deposited. As with most upper elevation slopes in this snow climate, the snowpack in Maroon Bowl is usually categorized as structurally weak, especially where there is shallower snowpack on windward slopes. However, considerable differences in snowpack structure and distribution would occur between the northerly and more southerly facing aspects of the bowl. Most of the upper ponions of Maroon Bowl are devoid of timber. The only significant tree cover to be found on the upper slope is a small patch located approximately in the center of the bowl. This general lack of trees indicates that, as with Highland Bowl, it may be possible for much of the upper ponions of this drainage to release at one time in a large avalanche event. The large expanse of upper Maroon Bowl, combined with the steep terrain along the sides of this drainage, suggest that the total area that could release in a single event could be greater than in Highland Bowl. Since the ground surface in the upper bowl is generally fairly smooth, significant avalanche activity may occur even under moderately sha1Iow snowpack conditions. The combination of a steep, wide staning zone with relatively few natural anchors, substantial venical relief, and an inaeasingly confined track: results in large, destructive avalanches that run to Maroon Creek perhaps as often as twice every 5 years. Smaller avalanches that run as far as the 10,OOO-foot level where the track oarrows are most likely a fairly common event. Section III H"""", Heallh oM Safety - Avalan;;he COnJrol 27