Cal. Health & Safety Code § 25299.53

(a) A regional board or a local agency taking, or contracting for, corrective action pursuant to subdivision (f) of Section 25296.10 in response to an unauthorized release from an underground storage tank subject to this chapter shall, before commencing the corrective action, take both of the following actions:
1. (1) The regional board or local agency shall notify the board of the planned corrective action. If an owner, operator, or other responsible party is taking the corrective action in accordance with Section 25296.10, the regional board or local agency shall not initiate a corrective action pursuant to this chapter or Chapter 6.7 (commencing with Section 25280).
2. (2) If an owner, operator, or other responsible party is not taking or has not taken the action specified in paragraph (1), the regional board or local agency shall submit the estimated cost of the corrective action to the board, which shall approve or disapprove the reasonableness of the cost estimate. The regional board or local agency shall obtain approval of the corrective action and the cost estimate before taking, or contracting for, any corrective action.
(b) If the board approves the request of the regional board or local agency made pursuant to paragraph (2) of subdivision (a), the board shall, after making the determination specified in subdivision (c), pay for the costs of corrective action performed by a regional board, local agency, or qualified contractor.
(c) The board shall not make any payment pursuant to subdivision (b) unless the board determines that the owner, operator, or other responsible party of the tank has failed or refused to comply with a final order for corrective action issued pursuant to Section 25296.10 with respect to the unauthorized release of petroleum from the tank.
(d) Upon making any payment to a regional board or local agency pursuant to subdivision (b), the board shall recover the amount of payment pursuant to Section 25299.70.