Colo. Rev. Stat. § 30-5-110
Chaffee county: Commencing at a point on the summit of the snowy range, at the northwest corner of the county of Park, and running due west to the western boundary of the state; thence south, on said boundary, to the summit of the Sierra La Plata, or the northwest corner of Conejos county; thence easterly along the northern boundary of Conejos county to the one hundred and seventh degree of longitude; thence north, following said degree, to the northwest corner of Saguache county; thence east, along the north boundary of Saguache county, to the top of the range at the Poncho pass; thence northeasterly along the summit of the range, crossing the Arkansas river, at a point three miles below the mouth of the South Arkansas river; thence easterly to the summit of the range which divides the waters of the Platte and Arkansas rivers, along the summit of the range and western boundaries of the counties of Fremont and Park, in a northwesterly direction to the point of beginning.
C.R.S. § 30-5-110