Colo. Rev. Stat. § 37-20-121
In all actions, suits, and judicial proceedings in any court of this state, the court shall take judicial notice of the organization and existence of any drainage district of this state, from and after the filing for record in the office of the county clerk and recorder of the certified copy of the order of the board of county commissioners mentioned in section 37-20-117. A certified copy of said order shall be prima facie evidence in all actions, suits, and proceedings in any court of this state of the regularity and legal sufficiency of all acts, matters, and proceedings therein recited and set forth. Any such drainage district, in regard to which any such order may be entered and such certified copy thereof so filed for record, which has exercised the rights and powers of such a district and which has in office a board of directors exercising the duties of its office and the legality or regularity of the formation or organization of which shall not have been questioned by proceedings in quo warranto instituted in the district court of the county in which such district or the greater portion thereof is situated, within one year from the date of such filing, shall be conclusively deemed to be a legally and regularly organized, established, and existing drainage district within the meaning of articles 20 to 30 of this title. The due and lawful formation and organization of said district shall not thereafter be questioned in any action, suit, or proceeding whether brought under the provisions of articles 20 to 30 of this title or otherwise.
C.R.S. § 37-20-121