Colo. Rev. Stat. § 32-4-538
It is hereby declared that a district shall be the exclusive agency for the acquisition and operation of a sewage disposal system within a district, except as in this part 5 otherwise provided or authorized, and that no sewage disposal system or other facility for the collection, treatment, or disposal of sewage arising within a district, including any sewage treatment or disposal facilities of a municipality, shall be acquired or improved after a district is organized, unless the district gives its consent thereto and approves the plans and specifications therefor, except for any acquisition or improvement of any sewer collection facilities or sewer system, but not sewage treatment or disposal facility or sewage disposal system, or any part thereof, owned by a municipality at any point above the connection of such collection facilities or sewer system with any sewage disposal system or other project of the district. Each district is empowered by this part 5 to give such consent and approval, subject to the terms and provisions of any agreement with any holder of securities.
C.R.S. § 32-4-538