All bonds shall be payable in lawful money of the United States at the office of the county treasurer of the county, and shall bear interest at a rate not to exceed 6 percent per annum, which shall be payable semiannually. Not less than one-thirtieth part of the total issue of bonds shall be payable each year, commencing not more than five years after the date of the bond issue.
(Added by Stats. 1949, Ch. 1147.)