Colo. Rev. Stat. § 31-25-541
The governing body, from time to time as work proceeds in a local improvement district, may authorize the issuance of interim warrants: For not to exceed ninety percent in value of the work theretofore done upon estimates of the engineer of the municipality; after completion of the work and acceptance thereof by the engineer of the municipality and by the governing body, for one hundred percent of the value of the work so completed; and, where improvements in the district require the acquisition of property, for an amount not exceeding the value of the property. The warrants may be issued to a contractor to apply at par value on the contract price for the improvements or to the owner of the property to apply at par value on the property price. The warrants may also be issued and sold at not less than par value in such manner as the governing body may determine, and the proceeds may be used to apply towards payment of the contract price and property price. Interim warrants shall bear interest from date of issue until paid at such rate as may be fixed by the governing body. Interest accruing on interim warrants shall be included as a cost of the improvements in the local improvement district. Interim warrants and interest thereon shall be paid by the issuance of or by proceeds from the sale of special improvement bonds issued or in cash received from the payment of assessments not pledged to the payment of the bonds or from any of such sources.
C.R.S. § 31-25-541