Cal. Water Code § 31034

If a public utility subject to the control and regulation of the Public Utilities Commission petitions the Public Utilities Commission to extend its water service or to establish water service within a district or any area served by a district, prior to acting on the petition the Public Utilities Commission shall notify the district of such petition where the district has previously filed with the public Utilities Commission a request to be notified of such petitions which request contains a description of the boundaries of the district and any area outside of the district boundaries which is served by the district.