Colo. Rev. Stat. § 37-44-148
Any person interested in said district, or in the issue or sale of said bonds, may move to dismiss or to answer said petition. The Colorado rules of civil procedure respecting motions to dismiss and answer to a verified complaint shall be applicable to a motion to dismiss and answer said petition. The person so moving or answering said petition shall be the defendant to the special proceeding, and the board of directors shall be the plaintiff. Every material statement of the petition not specifically contradicted by the answer for the purpose of said special proceedings shall be taken as true, and each person failing to answer the petition shall be deemed to admit as true all the material statements of the petition. The rules of pleading and practice relating to appeals and appellate review as provided by law and the Colorado appellate rules which are not inconsistent with the provisions of this article are applicable to the special proceedings.
C.R.S. § 37-44-148