CPUC DIVISION 6-14402
A district or any interested person may bring an action pursuant
to Chapter 9 (commencing with Section 860) of Title 10 of Part 2 of the Code of
Civil Procedures to determine the validity of district rates or charges.
Nothwithstanding any other provision of law, any judicial action or proceeding to attack, review, set aside, void, or annul an ordinance, resolution or motion fixing or changing rates for the commodities or service furnished by a district shall be commenced within 120 days of the effective date of the ordinance, resolution, or motion.
Code of Civil Procedure; Chapter 9, Title 10, Part 2, Section 860: A public agency may upon the existence of any matter which under any other law is authorized to be determined pursuant to this chapter, and for 60 days thereafter, bring an action in the superior court of the county in which the principal office of the public agency is located to determine the validity of such matter. The action shall be in the nature of a proceeding in rem.