LOCATION, PRESTIGE & ELEGANCE. Dercum's Dash on the Mountain is a destination community that is unrivaled in Summit County. The opportunity to build slope side in a private Ski-in/Ski-out community of Single Family BRAND NEW CUSTOM residences seldom presents itself. Highest quality on trend construction in Keystone's most prestigious community. Quietly secluded in the National Forest. Steps away from River Run Slopes & Gondola. USA Today rated Keystone #1 IN 10 Best US ski resorts for families.