Colo. Rev. Stat. § 32-11-679
Whenever the urban district issues assessment debentures or assessment bonds to obtain funds to pay for any project which has been actually acquired or improved, or both acquired and improved, and the assessments levied therefor fail to be valid or sufficient in whole or in part and a new assessment or reassessment has been levied and confirmed, as provided in sections 32-11-668 to 32-11-679, then the urban district is directed to apply all moneys derived from such assessments, new assessments, and reassessments to the payment of such assessment securities according to their tenor. The securities issued for any project actually acquired or improved, or both acquired and improved, shall be valid and binding obligations of the district, payable out of such assessments, new assessments, and reassessments, which shall be levied and relevied until payment in full has been made, as provided in section 32-11-624.
C.R.S. § 32-11-679