Cal. Water Code § 21560

If an order made pursuant to this article changes the number of divisions, the terms of office of all directors shall expire at noon on the first Friday in December following the next general district election after the order, and the directors elected at that election shall be equal in number to the number of divisions as changed and these directors shall at their first meeting classify themselves and determine the length of their respective terms in the manner provided in subdivision (c) of Section 10505 of the Elections Code.