Colo. Rev. Stat. § 37-42-140
This article 42 applies only to irrigation districts organized after April 7, 1921, and no existing laws in any manner relating to irrigation districts apply to or affect irrigation districts organized after that date, but existing laws and all amendments thereto made after that date remain in and have full force and effect as to all irrigation districts organized prior to April 7, 1921. However, whenever landowners of a majority of the number of acres of the irrigable land in any irrigation district organized prior to April 7, 1921, petition the board of directors to call a special election for the purpose of submitting to the landowners entitled to vote at elections of the irrigation district a proposition to vote, at any regular or any special election called and notice given for such purpose, upon the question whether the irrigation district shall thereafter operate under this article 42, and if two-thirds of the landowners of the irrigation district voting upon the question vote in favor of coming under this article 42, upon the filing of a statement of the results of the election in the manner provided by section 37-41-112, the irrigation district is thereafter governed by this article 42. The election of the district to come under this article 42 does not invalidate any act or proceeding previously done under the laws governing the irrigation district prior to the election and does not impair any obligation of the irrigation district or any right thereunder.
C.R.S. § 37-42-140