Health & Saf. Code, § 6497

(1) The sanitary board of sanitary districts may classify all the places of employment in or under the district, and in or under all the offices and departments of the district, with reference to the examinations hereinafter provided for. The places so classified by the sanitary board may constitute the classified civil service of the district, and no appointment to any such place shall be made except according to the rules hereinafter mentioned.

(2) The sanitary board may make rules to carry out the purposes of this section, and for examinations, appointments, promotions, and removals, and may from time to time make changes in existing rules. All rules and all changes therein shall be forthwith printed for distribution by the sanitary board.

(3) The examinations shall be practical in their character, and shall relate to those matters only which will fairly test the relative capacity of the persons examined to discharge the duties of the positions to which they seek to be appointed, and shall include, when appropriate, tests of manual or professional skill. The selection of laborers shall be governed by priority of application as far as may be practicable. No questions in any examination shall relate to political or religious opinions or affiliations. The sanitary board shall control all examinations.