Mont. Code Ann. § 69-3-503

All applications to the commission hereunder shall be disposed of promptly and in any event within 30 days after petition is filed with the commission unless, for good cause, it is necessary to continue consideration thereof for a longer period. Whenever such application is continued beyond said 30-day period, the commission shall enter its order effecting such continuance and stating fully therein the facts requiring continuance for a designated period of time.