Mont. Code § 85-7-1924
A person who in any manner interferes with the commissioners of an irrigation district or their lawful agent or employee in the carrying out of the powers conferred by 85-7-1921 through 85-7-1925 or who changes or tampers with any lock box, headgate, or other device for the apportionment or distribution of water installed by or under the authority of the commissioners or who in any manner obstructs or changes the flow of water in the distribution system of any irrigation district without authority of the commissioners of the district is, in the discretion of the commissioners, subject to a forfeiture of the person's right to the delivery of water through the distribution system of the district as long as the acts continue and is guilty of obstructing a public officer or criminal mischief, as appropriate, and is punishable as provided by 45-6-101 or 45-7-302, as applicable.
§ 85-7-1924, MCA