Mont. Code Ann. § 50-60-515

A person who works in the field of plumbing or maintains or conducts a plumbing business or an individual who connects or disconnects plumbing from a public water or sewer system in violation of any provisions of this part or at a time when the person is not exempt from the provisions of this part pursuant to the provisions of a duly enacted and subsisting ordinance of a city or town is guilty of a misdemeanor and, upon conviction in any court of competent jurisdiction, shall be punished by a fine of not less than $10 and not more than $100 for each separate offense. However, this part may not be construed to apply to or affect plumbing or pipefitting as indicated in the exceptions under 37-69-102 and 50-60-503.