It ended at Lake Sepasco . Part of the trail from Rhinebeck to Lake Sepasco follows about the same path that is today taken by Route 308 . Indicated by artifacts found near Lake Sepasco , a small lake along NY 308 , the highway began its history in about 1685 , when a group of Native Americans called the Sepasco built the Sepasco Trail ; this trail ran from the Hudson River , eastward through modern-day Rhinebeck ( then Sepasco or Sepascoot ) , and ended at Lake Sepasco , following roughly Route 308 and its side roads .