Whenever the board deems it necessary for the district to incur a bonded indebtedness in addition to that incurred at the time of the formation of the district for any of the purposes of the district, the board shall, by resolution, so declare and state the proposition to be submitted to the electors, the purpose for which the proposed debt is to be incurred, the amount of the debt to be incurred, the maximum term the bonds proposed to be issued shall run before maturity, which shall not exceed 40 years, and the maximum rate of interest to be paid, which shall not exceed 8 percent per year, payable semiannually.