Cal. Pub. Util. Code § 1504
Just compensation for the property so taken for public purposes shall be as may be mutually agreed by the political subdivision and the private utility or as ascertained and fixed by a court of competent jurisdiction pursuant to the laws of this state relating to eminent domain, including consideration of the useful value to the political subdivision of the property so taken.
Whenever the compensation by a political subdivision under this section is an amount equal to the just compensation value of all the property of the private utility in the operating system that the private utility employs in providing water service to the service area, the political subdivision may, by resolution, provide for the acquisition of all such property.
A political subdivision engaged in activities set forth in Section 1503 shall pay just compensation for the property so taken for public purposes.
Ca. Pub. Util. Code § 1504