85-7-1951. United States contracts -- loans, sinking fund, and investment. The board of commissioners of any irrigation district established and organized under and by virtue of the laws of Montana, whenever deemed advisable and to the interest of the district, shall have the power and authority to enter into any obligation or contract with the United States under any act of congress and the rules and regulations established thereunder, providing for or permitting such obligation or contract, for the purpose of obtaining from the United States a loan of money to be used by the district for the liquidation of bonded or other outstanding indebtedness of the district or for doing or causing to be done, under the supervision of the secretary of the interior of the United States, any construction, betterments, or repair work necessary to place the irrigation system of the district in good operating condition. The board shall also have the power and authority to create, by proper levy and collection of assessments, a sinking fund which shall be available for the construction of betterments to the irrigation system of the district, as may become necessary during the term of any contract made hereunder. Said sinking fund for said purpose, which shall be designated the ".... District Sinking Fund for Betterments", shall be in such an amount and shall be created within such time as may be agreed upon between the district and the United States. The board shall also have the power and authority to invest any surplus in the sinking fund herein provided for in legal investments backed, insured, or guaranteed by the United States or the state of Montana, including federal and state agency obligations.