Mont. Code Ann. § 90-7-306

All money received pursuant to this chapter, whether as proceeds from the sale of bonds, notes, or other obligations or as revenue or receipts, are trust funds to be held and applied solely as provided in this chapter. Any officer with whom or any bank or trust company with which such money is deposited shall act as trustee of the money and shall hold and apply it for the purposes of this chapter, subject to such regulations as this chapter and the resolution authorizing the bonds, notes, or other obligations of any issue or the trust agreement securing the obligations may provide.