Cal. Pub. Util. Code § 2720

(a) The commission shall use the standard of fair market value when establishing the rate base value for the distribution system of a public water system acquired by a water corporation. This standard shall be used for ratesetting.
1. (1) For purposes of this section, “public water system” shall have the same meaning as set forth in Section 116275 of the Health and Safety Code.
2. (2) For purposes of this section, “fair market value” shall have the same meaning as set forth in Section 1263.320 of the Code of Civil Procedure.
(b) If the fair market value exceeds reproduction cost, as determined in accordance with Section 820 of the Evidence Code, the commission may include the difference in the rate base for ratesetting purposes if it finds that the additional amounts are fair and reasonable. In determining whether the additional amounts are fair and reasonable the commission shall consider whether the acquisition of the public water system will improve water system reliability, whether the ability of the water system to comply with health and safety regulations is improved, whether the water corporation by acquiring the public water system can achieve efficiencies and economies of scale that would not otherwise be available, and whether the effect on existing customers of the water corporation and the acquired public water system is fair and reasonable.
(c) The provisions of subdivisions (a) and (b) shall also be applicable to the acquisition of a sewer system by any sewer system corporation or water corporation.
(d) Consistent with the provisions of this section, the commission shall retain all powers and responsibilities granted pursuant to Sections 851 and 852.