Colo. Rev. Stat. § 29-8-105
When any improvement authorized to be made by any governing body by the terms of this article is ordered, the governing body shall provide for the apportionment of the cost and expenses thereof as in its judgment may be fair and equitable in consideration of the benefits accruing to the abutting, adjoining, contiguous, and adjacent lots and lands, and to the lots and lands otherwise benefited and included within the improvement district formed. Each lot and parcel of the land shall be separately assessed for the cost and expenses thereof in proportion to the number of square feet of such lands and lots abutting, adjoining, contiguous, and adjacent thereto or included in the improvement district, or assessed upon a frontage, zone, or other equitable basis, in accordance with the benefits, as the same may be determined by the governing body. The entire cost of the improvement may be assessed against the benefited property as provided in this article or if money for paying part of such cost is available from any other source, the money so available may be so applied and the remaining cost so assessed against the benefited property. The cost and expenses to be assessed as provided in this article shall include the cost of the improvement, engineering and clerical service, advertising, cost of inspection, cost of collecting assessments, and interest upon bonds if issued, and for legal services for preparing proceedings and advising in regard thereto. Fee lands and property of public entities, such as the federal government, state of Colorado, or any county, city, or town, shall not be considered as lands or property benefited by any improvement district, and unless such public entity within the boundaries of an improvement district consents in writing, filed before the governing body adopts the resolution provided for in section 29-8-109, the lands and property of such public entity shall not be subject to assessment for the payment of any of the cost or expense of such improvement.
C.R.S. § 29-8-105