Mont. Code Ann. § 87-1-287

87-1-287 . Placement of warning sign in water legally accessible to public -- liability limitation -- role of department. (1) Unless acting with gross negligence, an individual or a nonprofit organization is not liable for civil damages resulting from the individual's or organization's placement of a sign or marker warning of a hazard in water legally accessible to the public as long as:

(a) the sign or marker is a white plastic milk bottle attached by a cord to the hazard or is a sign or marker approved by the department;

(b) the sign or marker contains or bears the name and telephone number of the individual or nonprofit organization that placed it;

(c) the individual or nonprofit organization maintains or removes the sign or marker when dictated by changing water conditions or seasonal changes; and

(d) the individual or nonprofit organization places the sign or marker only for the purpose of identifying hazards.

(2) (a) The provisions of this section are not intended to prohibit the placement of nonhazard signs or markers for waterskiing, diving, safe channels, or swimming areas or for posting speed limits.

(b) The department shall inform members of the public involved in the recreational use of the waters of this state of the placement, use, and significance of signs or markers warning of hazards in the water that are placed by individuals or nonprofit organizations pursuant to the provisions of this section.

(3) The provisions of this section apply only to the waters of this state that have not been determined to be navigable for purposes of federal jurisdiction over navigation aids.