Montana Partition Fence and Boundary Fence Law

70-16-205 . Monuments and fences -- mutual obligation of adjoining owners. (1) Coterminous owners are mutually bound equally to maintain: (a) the boundaries and monuments between them; (b) the fences between them, unless one of them chooses to let that owner's land lie without fencing, in which case if that owner afterwards encloses it, that owner shall refund to the other owner a just proportion of the value, at that time, of any division fence made by the other owner. However, using land for grazing or pasturage of any kind must be considered a usage of the land, and the land may not be considered as lying idle under the provisions of this section. (2) Except as provided by prescription, custom, or agreement between coterminous owners, each coterminous owner shall maintain all fencing to the right of the midpoint of the common boundary line as viewed from the owner's land. If the land of one owner is entirely surrounded by the land of another, each owner shall maintain all fencing to the right, as viewed from the owner's land, of the northeastern corner of the surrounded land or, if there is more than one northeastern corner, then from the northernmost northeastern corner to a point midway around the surrounded land. If there is a substantial difference in terrain or topographical features of the land between the coterminous owners, responsibility for maintaining the fence must be determined by mutual agreement with consideration given to factors such as cost and time.