Mont. Code Ann. § 85-7-108

The finding and order are conclusive upon all the owners of lands within the district that they have assented to and accepted the applicable provisions of this chapter and are final unless appealed from to the supreme court within 60 days from the day of entry of the order. A copy of the order, duly certified to by the clerk of the district court, shall be filed for record within 30 days after the order is made and entered with the county clerk and recorder of the county where the lands included within the district are situated. Lands not situated in the county in which the copy is filed shall be omitted from the copy.