California Code, Health and Safety Code - HSC § 2025

(a) Under no circumstances shall a board of trustees consist of less than five members. Except as provided in Section 2026, the number of members who represent the unincorporated territory of a county may not exceed five members.

(b) A board of trustees may adopt a resolution requesting the board of supervisors of any county that contains territory within the district to increase or decrease the number of members of the board of trustees who represent the unincorporated territory of that county within the district. The resolution shall specify the number of members and the areas of the unincorporated territory for which the board of trustees requests the increase or decrease.

(c) Within 60 days of receiving a resolution adopted pursuant to subdivision (b), the board of supervisors shall order the increase or decrease in the number of members of the board of trustees, consistent with the board of trustees' resolution.

(d) If the board of supervisors orders an increase in the number of members of the board of trustees, the board of supervisors shall appoint a person or persons to the board of trustees and specify their term of office, consistent with the requirements of this chapter. If the board of supervisors orders a decrease in the number of members of the board of trustees, the board of supervisors shall designate the trustee or trustees whose office shall be eliminated at the termination of the trustee's current term of office. Any trustee whose office is designated to be eliminated shall continue to serve until his or her term of office expires.