Colo. Rev. Stat. § 30-5-117
So much of the county of Gunnison as is included within the following described boundaries shall be set apart and is hereby established as a county, with the legal capacity and functions of other counties of this state, to be called the county of Delta:
Beginning at a point two miles south of the third correction line extended west to a point of intersection with the 107 degrees, 30 minutes west longitude; thence due north along said degree of longitude to the divide between the headwaters of the Colorado and North Fork of the Gunnison rivers; thence along said divide in a southwesterly direction to a point on the extreme southwestern extremity of the Grand Mesa; thence in a southwesterly direction to the mouth of the Rio Dominguez; thence due south to a point two miles south of an extension of the third correction line; thence due east parallel with said extension of the third correction line to place of beginning.
C.R.S. § 30-5-117