Mont. Code § 77-2-206
If any state land is exchanged on which there are improvements belonging to a lessee and some person other than the lessee is the transferee, that person shall settle with the lessee for all improvements on the land belonging to the lessee before the exchange is completed. The provisions of 77-6-301 through 77-6-303 and 77-6-306 relating to the payment and settlement for improvements on state lands between a former lessee and a new lessee apply to the settlement between a lessee and the transferee in an exchange. If settlement is not reached within 6 months of the date of exchange, all improvements become the property of the state unless the department for good cause shown grants both parties additional time in which to exhaust arbitration.
§ 77-2-206, MCA