Colo. Rev. Stat. § 31-25-822
Subsequent to the organization of an authority, additional property may be included in the district. Proceedings for inclusion shall be initiated by petition to the board of the authority signed by the owner or owners in fee of each parcel of land adjacent to the existing district sought to be included. Any such petition shall include evidence satisfactory to the board concerning title to the property and an accurate legal description thereof. If the board approves said application, it shall then submit the same to the governing body of the municipality. If the governing body also approves said application, it shall then, at a regular or special meeting by amendment to the ordinance treating the authority, redescribe the district so as to include the additional property as described in the petition. From the effective date of said amendment such additional property shall be included within the district and shall be subject to any taxes thereafter imposed by the municipality for the use and benefit of the authority.
C.R.S. § 31-25-822