Mont. Code § 76-15-508
The board of supervisors of a conservation district may invest any surplus funds of the district not needed for immediate use in the operations of the district or its activities, to pay bonds or coupons, or to meet current expenses in interest-bearing bonds or securities of the United States or of any agency of the United States if the bonds are guaranteed by the United States or in bonds of the state of Montana or any county or municipal corporation in said state. The board of supervisors of said district may require any funds of the district to be deposited with such depository or bank as may be designated by the board and likewise shall have authority to require the treasurer of the district to take from such depository a bond with corporate surety to ensure payment of any such deposit or to require such depository to pledge securities of the same kind as the district is authorized to invest its funds in to ensure payment of any such deposit.
§ 76-15-508, MCA