Colo. Rev. Stat. § 32-4-407
The boundaries of any district organized under the provisions of this part 4 may be changed in the manner prescribed in this part 4, but the change of boundaries of the district shall not impair or affect its organization or its rights in or to property, or any of its rights or privileges whatsoever; nor shall it affect or impair or discharge any contract obligation, lien, or charge for or upon which it might be liable or chargeable had such change of boundaries not been made. The incorporated areas of cities, towns, water districts, and unincorporated areas lying within the boundaries of any district organized under this part 4, as established by the original ordinances of initiating municipalities and from time to time by action of the board of directors, may be added to the district.
C.R.S. § 32-4-407