Cal. Health & Safety Code § 79315

Except as provided in subdivision (a) of Section 79325, the department or the regional board shall require any responsible party who is required to comply with operation and maintenance requirements as part of a response action, to demonstrate and to maintain financial assurance in accordance with this article. The responsible party shall demonstrate financial assurance prior to the time that operation and maintenance activities are initiated and shall maintain it throughout the period of time necessary to complete all required operation and maintenance activities.