Cal. Pub. Util. Code § 12054

The civil service provisions of this chapter do not apply to any district until such time as it has operated, controlled, or used works or parts of works for the providing of any of the utility services specified in this division. A civil service system may, however, be adopted at any time after the district commences to operate, control, or use works or parts of works for the providing of any of the utility services specified in this division, and such system shall be adopted within six months thereafter.