Cal. Pub. Util. Code § 99371

Any action, suit or proceeding of any kind or nature in which the validity of any of the proceedings taken under the provisions of this article is questioned or attacked, shall be filed within 30 days after the day of the adoption of the resolution providing for the issuance of the bonds and in case such action is not brought raising such issue within such period, then thereafter all persons whatsoever shall be barred in any action, suit or proceeding from pleading, asserting or claiming that any of the proceedings or other actions herein specified, were defective, faulty or invalid in any respect.