California Code, Business and Professions Code - BPC § 103

Each member of a board, commission, or committee created in the various chapters of Division 2 (commencing with Section 500) and Division 3 (commencing with Section 5000), and in Chapter 2 (commencing with Section 18600) and Chapter 3 (commencing with Section 19000) of Division 8, shall receive the moneys specified in this section when authorized by the respective provisions.

Each such member shall receive a per diem of one hundred dollars ($100) for each day actually spent in the discharge of official duties, and shall be reimbursed for traveling and other expenses necessarily incurred in the performance of official duties.

The payments in each instance shall be made only from the fund from which the expenses of the agency are paid and shall be subject to the availability of money.

Notwithstanding any other provision of law, no public officer or employee shall receive per diem salary compensation for serving on those boards, commissions, or committees on any day when the officer or employee also received compensation for the officer or employee's regular public employment.