Cal. Pub. Util. Code § 15951

At an election held in the district on the next established election date not less than 74 days after its formation a board of directors shall be elected, to consist of as many members as there are territorial units in the district and as many additional members, not less than three nor more than four, as are required to constitute a board composed of an odd number of directors. Where the district lies entirely in one county the number of directors shall be three, elected at large.