Cal. Water Code § 13303

Cease and desist orders of the board shall become effective and final upon issuance thereof. Copies shall be served forthwith by personal service, certified mail, or by any method of physical delivery that provides a receipt, upon the person being charged with the violation of the requirements, and by first class or electronic mail upon other affected persons who appeared at the hearing and requested a copy. For purposes of this section, “physical delivery that provides a receipt” includes physical delivery methods that provide electronic confirmation of delivery to the intended address.