Cal. PUC § 2707

For the purpose of determining the status of any person, firm, or corporation, their lessees, trustees, receivers or trustees appointed by any court, owning, controlling, operating, or managing any water system or water supply within this state, the commission may hold hearings and issue process and orders in the manner and to the same extent as provided in Part 1 (commencing with Section 201), and the findings and conclusions of the commission on questions of fact arising under this chapter are final and not subject to review, except as provided in Part 1 (commencing with Section 201).