Colo. Rev. Stat. § 37-31-150
For the half-yearly interest accruing on such bonds actually issued and delivered, the board of directors of said district shall levy annually a sufficient tax to fully discharge such interest, and, for the ultimate redemption of such bonds, they shall levy annually such tax upon all the taxable property of such district as will create a yearly fund sufficient to pay the bonds maturing in such year. All taxes for interest on and for the redemption of such bonds shall be paid in cash only and shall be kept by the district treasurer as a special fund to be used in payment of interest on, and for the payment of, such bonds annually, and such tax shall be levied and collected as other taxes. If the board of directors of the district fails to levy and certify such taxes to the board of county commissioners of Mesa county, it nevertheless is the duty of such board of county commissioners to levy such taxes.
C.R.S. § 37-31-150