Mont. Code § 82-11-207
An order of the board providing for unit operations may not become effective unless the plan for unit operations prescribed by the board has been approved in writing by those persons who under the board's order will be required to pay at least 70% of the costs of the unit operations and also by the persons owning at least 60% of the production or proceeds of the unit operations that will be credited to interests that are free of cost, such as royalties, overriding royalties, and production payments, and the board has made a finding, either in the order providing for unit operations or in a supplemental order, that the plan for unit operations has been approved. However, if one owner who is obligated to pay costs of the unit operation owns 70% or more but less than 100%, the approval of that owner and at least one other owner is required, and if one person entitled to production or proceeds of the production that will be credited to interests that are free of costs owns 60% or more but less than 100%, the approval of that person and at least one other owner is required. If the plan for unit operations has not been approved at the time the order providing for unit operations is made, the board shall, upon application and notice, hold supplemental hearings that may be required to determine if and when the plan for unit operations has been approved. If the requisite number of owners and persons and the requisite percentage of interests in the unit area do not approve the plan for unit operations within a period of 6 months from the date on which the order providing for unit operations is made, the board shall revoke the order unless, for good cause shown, the board extends the time.
§ 82-11-207, MCA