In addition to other powers authorized by law, the board of directors of a natural resources district encompassing a city of the metropolitan class, upon an affirmative vote of two-thirds of the members of the board of directors, may issue negotiable bonds and refunding bonds of the district, entitled flood protection and water quality enhancement bonds, with terms determined appropriate by the board of directors, payable from an annual special flood protection and water quality enhancement bond levy upon the taxable value of all taxable property in the district. Such special bond levy is includable in the computation of other limitations upon the district’s tax levy and shall not exceed one cent on each one hundred dollars of taxable valuation annually on all of the taxable property within the district without approval by a majority of registered voters of the district at an election in accordance with the Election Act called by the board of directors and held in conjunction with a statewide primary or general election.