Colo. Rev. Stat. § 30-5-153
Park county: Commencing at a point where the second correction line south intersects the Platte river; thence south to the third correction line south; thence west to the summit of the snowy range, east of the Arkansas river; thence in a northerly direction along the divide between the Arkansas and Platte rivers, and around the headwaters of the Platte river and its tributaries; thence easterly along the snowy range dividing the waters of the Platte from the waters of the Blue, to the point of intersection with the first correction line south; thence east on said correction line to the western boundary of Jefferson county; thence south on said boundary to the Platte river; thence up the center of said river to the place of beginning.
C.R.S. § 30-5-153
Pursuant to §§ 30-6-105 to 30-6-109, inclusive, there is recorded in the office of the clerk and recorder of Park County in book 70, page 560, and in the office of the clerk and recorder of Jefferson County in book 140, page 400 (indexed in book 2 - Miscellaneous Papers - in the office of the secretary of state), a proclamation showing attachment to Park County and detachment from Jefferson County of territory described as follows:
"Beginning at the intersection of the boundary line between Park and Jefferson Counties with the center line of the South Platte River, about two miles above Lake George, thence down the said Platte River along its center line to intersection of said center line with the Second Correction Line South, thence westerly along said Correction Line to its intersection with the boundary line between Park and Jefferson Counties, thence along said boundary line to point of beginning."