Colo. Rev. Stat. § 37-41-127
For purposes of defraying the expenses of the organization of the district, and the care, operation, management, repair, and improvement of all canals, ditches, reservoirs, and works, including salaries of officers and employees, the board may either fix rates of tolls and charges and collect the same of all persons using said canal and water for irrigation or other purposes, and in addition thereto may provide, in whole or in part, for the payment of such expenditures by levy of assessments therefor as provided in section 37-41-123, or by both tolls and assessment. In case the money raised by the sale of bonds issued is insufficient, and in case bonds are unavailable for the completion of the plans of works adopted, it is the duty of the board of directors to provide for the completion of said plans by levy of an assessment therefor in the same manner in which levy of assessments is made for the other purposes provided for in section 37-41-120.
C.R.S. § 37-41-127