California Code, Streets and Highways Code - SHC § 5660

No action, suit, or proceeding to set aside, cancel, avoid, annul or correct any assessment or reassessment, or to review any of the proceedings, acts, or determinations therein, or to question the validity of, or to enjoin the collection of the assessments or reassessments, or to enjoin the issuance of bonds to represent the same, shall be maintained by any person unless such action is commenced within 30 days after the recording of the warrant, diagram and assessment or reassessment, and thereafter all persons shall be barred from any such action or any defense of invalidity of the assessment or of bonds issued thereon or of the reassessment if such is made and of bonds issued thereon.