Elec. Code, § 10506

Whenever a district shall increase the number of divisions, if there are any, the terms of office of the offices of director thus created shall be determined by the governing body, but in no event shall the term designated by the governing body be for more than four years. The terms of office thus created shall be determined in such a manner as to keep as nearly equal as practicable the number of directors to be elected at each subsequent general district election. Upon the expiration of the term so designated by the governing body, the directorship shall be filled at the next general district election and general district elections held thereafter. The term of office of each subsequent director thus elected is four years or until his or her successor qualifies and takes office.