Mont. Code Ann. § 77-4-106

The board may, at any time prior to the execution and delivery of a geothermal lease or at any time during the life of the lease, require a lessee to file with the department a bond to protect the rights of the state. The bond shall be in form and amount prescribed by the board. The board may at any time require new or additional bonds if the interests of the state will not adequately be protected by the bond previously filed.