California Code, Public Resources Code - PRC § 3226

(a) Within 30 days after service of an order pursuant to Sections 3224 and 3225, or Section 3237, or if there has been an appeal from the order to the director, within 30 days after service of the decision of the director, or if a review has been taken of the order of the director, within 10 days after affirmance of the order, the owner or operator shall commence in good faith the work ordered and continue it until completion. If the work has not been commenced and continued to completion, the supervisor may appoint necessary agents to enter the premises and perform the work. An accurate account of the expenditures shall be kept. Any amount so expended shall constitute a lien against real or personal property of the operator pursuant to the provisions of Section 3423.Before performing such work, the division may impose a lien against the real or personal property of the operator pursuant to Section 3423 in an amount equal to an estimate of the cost of the work based on a bid from a contractor or previous costs to perform comparable work.

(b) Notwithstanding any other provisions of Section 3224, 3225, or 3237, if the supervisor determines that an emergency exists, the supervisor may order or undertake the actions the supervisor deems necessary to protect life, health, property, or natural resources.

(c) The division's accounting of actual or estimated costs to perform work ordered shall be served upon the operator by personal service or certified mail. For purposes of Section 3420, charges to an operator pursuant to this section for actual or estimated costs to perform work ordered are delinquent if not paid within 30 days after service of the accounting of costs.