Colo. Rev. Stat. § 30-20-414
All revenue bonds or other obligations payable solely from revenues of a water or sewer system, and any coupons appertaining thereto, appertaining to a water system, sewer system, or joint water and sewer system issued or purportedly issued prior to June 2, 1971, and all acts and proceedings had or taken or purportedly had or taken before that date, by or on behalf of any county under law or under color of law, preliminary to and in the authorization, execution, sale, and issuance of all water revenue bonds, sewer revenue bonds, and joint water and sewer revenue bonds, including any coupons appertaining thereto, the authorization and execution of all other contracts, and the exercise of other powers in this part 4, are validated, ratified, approved, and confirmed, except as provided in section 30-20-415, notwithstanding any lack of power, authority, or otherwise, other than constitutional, and notwithstanding any defects and irregularities, other than constitutional, in such securities, acts, and proceedings in such authorization, execution, sale, and issuance and in such exercise of powers; and such securities and other contracts are and shall be binding, legal, valid, and enforceable obligations of such county to which they appertain in accordance with their terms and their authorization proceedings.
C.R.S. § 30-20-414