Colo. Rev. Stat. § 37-44-139
Except with respect to claims coming within the provisions of article 10 of title 24, C.R.S., no claim shall be paid by the district treasurer until the same is allowed by the board, and only upon warrants signed by the president and countersigned by the secretary, which warrants shall state the date authorized by the board and for what purposes. If the district treasurer has not sufficient money on hand to pay such warrant when it is presented for payment, he shall endorse thereon "not paid for want of funds, this warrant draws interest from date at six percent per annum" and endorse thereon the date when so presented over his signature, and from the time of such presentation such warrant shall draw interest at the rate of six percent per annum. All claims against the district shall be verified, and the secretary of the district is authorized to administer oaths to the parties verifying said claims, the same as a notary public might do. The district treasurer shall keep a register in which he shall enter said warrants presented for payment, showing the date and amount of such warrants, to whom payable, the date of presentation for payment, the date of payment, and the amount paid in redemption thereof, and all warrants shall be paid in their order of presentation for payment to the district treasurer. All warrants shall be drawn payable to bearer the same as for county warrants.
C.R.S. § 37-44-139