California Code, Public Resources Code - PRC § 9356

(a) Except as provided in subdivision (b), directors shall be elected at large.

(b) A district may, by ordinance, provide for the election of directors by division. In order to reduce election costs, the divisions shall be established along the boundaries of existing voting precincts. Prior to adopting an ordinance pursuant to this subdivision, the text of the proposed ordinance, including proposed division boundaries, shall be published pursuant to Section 6066 of the Government Code, together with notice of the hearing at which the ordinance will be considered. At the time stated in the notice for the hearing, the board of directors shall consider the proposal and shall hear any and all objections thereto. If, after the hearing, the board determines it to be in the best interests of the district, it shall adopt the ordinance as proposed or as amended at the hearing. Directors in office at the time of adoption of the ordinance shall remain in office until the next general district election, at which a director shall be elected to each division established by the ordinance. The directors elected at that election shall meet and classify themselves by lot into two classes as nearly equal in number as possible. The term of office of those in the class having the least number shall expire at noon on the last Friday in November of the next even-numbered year after the year in which the meeting is held. The term of office of those in the other class shall expire at noon on the last Friday in November of the second even-numbered year after the year in which the meeting is held.

(c) If it is proposed to change the number of directors of a district divided into divisions, or if it is proposed to change the number of divisions in a district, that change shall be conditional upon adoption by the board of directors of a new or revised ordinance under subdivision (b) and the provisions and procedures of subdivision (b) shall be applicable thereto.

(d) Notwithstanding subdivisions (b) and (c), in any district in which directors are appointed pursuant to Section 9314or 9316, the board of supervisors of the principal county shall make the appointments by division, as called for in the ordinance adopted pursuant to subdivision (b), and those appointments shall become effective, and the terms of existing directors shall expire, on the same date as if the directors were elected.