Mont. Code § 67-11-105
The acquisition of any land or interest therein, pursuant to this chapter; the planning, acquisition, establishment, development, construction, improvement, maintenance, equipment, operation, regulation, and protection of airports and air navigation facilities, including the acquisition or elimination of airport hazards, and the exercise of any powers herein granted to authorities and other public agencies to be severally or jointly exercised are hereby declared to be public and governmental functions, exercised for a public purpose, and matters of public necessity. All land and other property and privileges acquired and used by or on behalf of any authority or other public agency in the manner and for the purposes enumerated in this chapter shall and are hereby declared to be acquired and used for public and governmental purposes and as a matter of public necessity.
§ 67-11-105, MCA