California Code, Public Utilities Code - PUC § 98168

(a) The district shall not require any employee, who is a member of a bona fide religion, body, or sect which has historically held conscientious objections to joining or financially supporting labor organizations, to join or financially support any public employee labor organization as a condition of employment.  However, that employee may be required, in lieu of paying periodic dues, fees, or assessments to a labor organization, to pay sums equal to those dues, fees, or assessments to a nonreligious, nonlabor charitable fund exempt from taxation under Section 501(c) (3)  [FN1] of the Internal Revenue Code (26 U.S.C. Sec. 501(c) (3)), chosen by the employee from a list of at least three qualifying funds, designated in a memorandum of understanding between the district and the labor organization or, if the memorandum of understanding fails to designate the funds, then to any qualifying fund chosen by the employee.  Proof of payments made pursuant to this section shall be made on a monthly basis to the district as a condition of continued exemption from the requirement of financial support to a labor organization.

(b) An exclusive representative may represent their bargaining unit members in employer-employee relations with the district, and employees shall have the right to be represented by their exclusive representative.