Mont. Code Ann. § 81-4-311
Duty to build and maintain fences
81-4-311 . Duty to build and maintain fences. Upon creation of a herd district pursuant to 81-4-301 , 81-4-304 , or 81-4-322 , fences must be constructed by the entities creating the herd district. Upon approving an annexation to an existing herd district pursuant to 81-4-310 , fences must be constructed by the entities being annexed into the herd district. All fences must be maintained pursuant to 70-16-205 . All fences must conform with the requirements of 81-4-101 . An action to enforce the provisions of this section may be brought by the aggrieved party in the district court in the county where the land is situated.