Colo. Rev. Stat. § 34-51-119
The board has power to raise money necessary to carry out the system of drainage adopted, and to otherwise accomplish the objects and purposes of this article, by the issue and sale of bonds, bearing interest not to exceed eight percent per annum, payable at the office of the county treasurer, in even sums of not less than five hundred dollars, and such bonds shall be a lien upon all property within the boundaries of the district made taxable under this article. The board may sell bonds from time to time in such quantities as may be necessary to carry out the objects and purposes of this article. Before making any sale the board shall, at a meeting, by resolution declare its intention to sell and shall cause such resolution to be entered in the minutes and notice of the sale to be given by publication thereof at least twenty days in a daily newspaper published in the city of Denver, and in any other newspaper, at its discretion. The notice shall state that sealed proposals will be received by the board at its office, for the purchase of the bonds, till the day and hour named in the resolution. At the time appointed the board shall open the proposals and award the purchase of the bonds to the highest responsible bidder and may reject all bids; but said board in no event shall sell any of said bonds for less than ninety-five percent of the face value thereof.
C.R.S. § 34-51-119