Colo. Rev. Stat. § 37-26-107
If the board of directors of any drainage district issuing or intending to issue refunding bonds desires to obtain the constructive consent of unknown and nonconsenting holders of bonds or claims for interest thereon desired to be retired or refunded under this article, such board of directors, before selling or otherwise disposing of any such refunding bonds, shall declare by resolution its intention of selling or otherwise disposing of the same and shall cause such resolution to be entered on its minutes and shall cause notice of sale or other disposition to be given by publication thereof at least once a week for four consecutive weeks in three newspapers published in the state of Colorado, one of which shall be a newspaper published in the city of Denver and one of which shall be a newspaper published in the county in which the office of the board of directors is situated.
C.R.S. § 37-26-107