Mont. Code Ann. § 77-6-101

It is hereby declared to be the policy of the state, that in the interest of accomplishing a sustained income for the school and other trust funds to be derived from land grant and other state lands, agricultural and grazing lands and town and city lots shall be appraised from time to time but not less than once during the term of every lease by competent appraisers. The purpose of such appraisals shall be to determine the rental value of agricultural lands and town and city lots, the general condition of the lands, and the carrying capacity of grazing lands.