(a) The chartered municipality form of local government on Rota, and, Tinian and Aguiguan, is hereby established. Local taxes paid to the chartered municipal governments of Rota, and, Tinian and Aguiguan, and Saipan may be expended for local public purposes on the island or islands producing those revenues. New agencies of local government may not be established without the affirmative vote of two-thirds of the persons qualified to vote from the island or islands to be served by the proposed agency of local government.