California Code, Public Utilities Code - PUC § 12055

(a) Officers elected by the people.

(b) Officers, assistant officers, and other persons and employees appointed by the board of directors.

(c) Temporary construction employees.

(d) Part-time employees.

(e) The unfilled positions (not to exceed 15) requiring peculiar and exceptional qualifications, including those of a scientific, professional, or expert character or of special confidence, as may be exempted from “district civil service” upon the recommendation of the general manager approved by the board.

(f) Limited-term employees appointed for a period not to exceed two years.  Limited-term appointments may be extended for an additional period not to exceed two years upon approval of the general manager.

(g) Employees occupying positions determined to be exempt from the district civil service pursuant to Section 11887.1.