The board shall adopt an ordinance, in accordance with Section 12815, calling an election for the purpose of submitting to the voters of the district the proposition as to whether or not the voters approve the addition of fluorine and fluorine compounds to the public water supply of the district, when a petition for the election has been filed with, and certified as sufficient by, the secretary of the district. The election shall be conducted in accordance with Section 12815. Petitions meeting the requirements of Sections 12814 to 12816, inclusive, shall be

in lieu of the initiative procedure provided by Article 1 (commencing with Section 9300) of Chapter 4 of Division 9 of the Elections Code.