Mont. Code Ann. § 76-15-601

Whenever the public interest or convenience may require and upon the petition of a county, city, town, cooperative grazing association, or other special purpose district or by more than 50% of the qualified electors affected thereby, the board of supervisors is hereby authorized and empowered to establish project areas for carrying out projects to accomplish one or more of the purposes of the district and within which area special assessments can be made for carrying out project purposes.