(2) Contract provisions for repayment of any loan from the United States, and the bonds securing the payment of the loan, if any are issued, may be of any term or denomination not exceeding 50 years and may call for the payment of interest not exceeding seven percent per annum, may provide for installments and for repayment of the principal at such times as may be required by federal law or as may be agreed upon between the district board and the United States agency. [2009 c.584 §18]