California Code, Health and Safety Code - HSC § 79730

(a)(1) Except as provided in paragraph (2) and subdivision (b), an action under Section 79650 for the recovery of costs incurred by the department or a regional board in carrying out or overseeing a response or corrective action pursuant to this part or Chapter 6.5 (commencing with Section 25100) of Division 20, or as otherwise authorized by law, shall be commenced within three years after completion of all response or corrective actions has been certified by the department or a regional board.

(2) If operation and maintenance is required as part of the response or corrective action, the action for recovery of costs incurred by the department or a regional board shall be commenced within three years after completion of operation and maintenance has been certified by the department or a regional board.