California Code, Water Code - WAT § 81330

Any action or proceeding in which the validity of the formation of the agency, or any of the proceedings in relation thereto, is contested, questioned, or challenged shall be commenced not later than 60 days from the date of the Secretary of State's certificate of formation. In the absence of that action or proceeding, the formation and legal existence of the agency, and all proceedings in relation thereto, shall be held to be in every respect valid, legal, and incontestable.