Mont. Code § 85-2-414
The right to conduct water from or over the land of another for any beneficial use includes the right to raise any water by means of dams, reservoirs, or embankments to a sufficient height to make the same available for the use intended, and the right to any and all land necessary therefor may be acquired upon payment of just compensation in the manner provided by law for the taking of private property for public use. If it is necessary to conduct the water across the right-of-way of any railroad, it shall be the duty of the owners of the ditch or flume to give 30 days' notice in writing to the owner or owners of such railway of their intention to construct a ditch or flume across the right-of-way of such railroad, the point at which the ditch or flume will cross the railroad, and the time when the construction of said ditch or flume will be made. If the owner or owners of such railroad or their agent fail to appear and attend at the time and place fixed in said notice, it shall be lawful for the owner or owners of the said flume or ditch to construct the same across the right-of-way of such railroad without further notice to said owner or owners of the railroad.
§ 85-2-414, MCA