Board members and alternates shall be appointed by the legislative body, unless the voters of the municipality decide at a regular or special meeting warned for that purpose that the Board members and alternates will be elected by the voters of the municipality. If the Board members and alternates are to be elected by the voters, the election shall take place biennially at the annual meeting of the municipality in the same manner as elections for the legislative body. If the Board members and alternates are to be appointed, the legislative body shall make its appointments by the end of March in the year in which the term of the preceding Board member expires. The clerk of the municipality shall certify its appointments to the Clerk of the District.