Cal. Rev. & Tax. Code § 40175

In addition to any other reports or returns required under this part, the board may by rule or otherwise require additional, supplemental or other reports from electric utilities, consumers, and any other person generating, purchasing, transmitting, distributing or consuming electrical energy, including verification of the information to be given on and the times for filing of such reports. For the purpose of carrying out its duties under Article 2 (commencing with Section 40031) of Chapter 2 of this part, the board may require such reports of estimates of future availability, generation, sales and consumption of electrical energy from such electric utilities and other persons as it may deem necessary. The board shall have full access to records of the Public Utilities Commission, and any political subdivision or public agency of this state that regulates, operates or owns an electric utility, which pertain to the generation, transmission, distribution, sale, purchase or consumption of electrical energy in this state.