The board of supervisors may, if in its judgment it seems best, issue negotiable bonds (1) not to exceed the amount of the total tax levy certified to the county clerk or clerks as provided by law, (2) in denominations of not less than one hundred dollars, (3) bearing interest payable semiannually, (4) to mature at annual intervals in not to exceed twenty years, and (5) with both principal and interest payable at the office of the county treasurer of the county in which the drainage district was organized, or at some convenient banking house or trust company office to be named in the bonds. The bonds and interest coupons shall be executed in the name of the district, and shall be signed by the chairman of the board of supervisors, attested with the seal of the drainage district and by the signature of the secretary of the board. Such bonds shall be made to run for not more than twenty years, and in case they are made to mature at different times within such period, the assessment shall be divided into as many installments as there are different dates of maturity. The installments shall be numbered consecutively as issued, and bear date at the time of their issue.