Cal. Water Code - WAT § 22670. Section 22670.
An action to determine the validity of any contract entered into for a period of more than three years or the levy of any assessment or of bonds, including whether or not the bonds when delivered to the person entitled to them under the terms of a contract will or do constitute valid obligations of the district as against all persons, may be brought pursuant to Chapter 9 (commencing with Section 860) of Title 10 of Part 2 of the Code of Civil Procedure.