The legislative body may fix a date, not more than two years from the date of issuance, for the earliest maturity of each issue or series of bonds. Beginning with the date of the earliest maturity of each issue or series, not less than one-fortieth of the indebtedness of such issue or series shall be paid every year; provided, however, the bonds of any issue or series may be made to mature and become payable in approximately equal total annual installments of interest and principal, during the term of the bonds computed from the first year in which any part of the principal shall mature to the date of final maturity, which annual installments may vary one from the other in amounts not exceeding in any year more than 5 percent of the total principal amount of the bonds of such issue or of the series thereof then proposed to be issued. The final maturity date shall not exceed 40 years from the time of incurring the indebtedness evidenced by each issue or series.
The bonds shall be payable at a place to be fixed by the legislative body and designated in the bonds, together with the interest on all sums unpaid on such date, interest to be paid semiannually, except that interest for the first year after the date of the bonds may be made payable at the end of said year, until the whole of the indebtedness shall have been paid. The principal and interest on the bonds shall be paid by the city treasurer in the manner provided by law for the payment of bonds of the city. Such bonds shall not be an obligation of the municipality issuing them but shall be payable from the funds of the district as herein provided and neither the municipality nor any officer thereof shall be holden for payment otherwise of their principal and interest.