Cal. Pub. Resources Code § 5538
The board shall appoint a general manager, who shall be the chief administrative officer of the district, and a controller, and may appoint other subordinate officers, and shall fix their compensation and duties. Such appointees shall hold office at the pleasure of the board. They shall give such bonds and in such amounts as the board may require. The board may consolidate any of such offices in one person. The board may also provide for an assistant to any officer of the district, who, when appointed by the board, may perform any act that his principal may perform, when authorized so to do by the board.
The board may from time to time contract for or employ any professional services required by the district, or by the board, or by any officers of the district.
Ca. Pub. Res. Code § 5538