Cal. Pub. Resources Code § 3224
The supervisor shall order those tests or remedial work as in the supervisor's judgment are necessary to prevent damage to life, health, property, and natural resources; to protect oil and gas deposits from damage by underground water; or to prevent the escape of water into underground formations, or to prevent the infiltration of detrimental substances into underground or surface water suitable for irrigation or domestic purposes, to the best interests of the neighboring property owners and the public. In addition to any cessation requirements or other limitations contained in applicable regulations or conditions of approval, an order to undertake remedial work under this section may include an order to cease and desist specified activities that threaten to damage life, health, property, or natural resources, including waters suitable for irrigation or domestic purposes, or that violate the requirements of this chapter or a regulation implementing this chapter. The order shall be in writing, signed by the supervisor. It shall be served upon the owner of the well, or the owner's local agent, either personally or by mailing a copy of the order to the post office address given at the time the local agent is designated. If a local agent has not been designated, the order shall be served by mailing a copy to the last known post office address of the owner, or if the owner is unknown, by posting a copy in a conspicuous place upon the property, and publishing it once a week for two successive weeks in some newspaper of general circulation throughout the county in which the well is located. The order shall specify the conditions sought to be remedied and the work necessary to protect the deposits from damage from underground water.
Ca. Pub. Res. Code § 3224