Mont. Code Ann. § 82-4-238

When one operator succeeds another at an uncompleted operation, either by sale, assignment, lease, or otherwise, the department may release the first operator from all liability under this part as to that particular operation if both operators have been issued a permit and have otherwise complied with the requirements of this part, and the successor operator assumes, as part of the obligation under this part, all liability for the reclamation of the area of land affected by the former operator.