Cal. Sts. & High. Code § 119

Any real property or interest therein which has passed to the State and has been accepted on behalf of the State by the department for highway purposes, inadvertently or by mistake, may be reconveyed to the persons entitled thereto. The reconveyance of any such real property or interest therein shall be executed by the director on behalf of the State. Such reconveyance shall not be made until the consideration originally received therefor by the grantor is first refunded or reconveyed to the State, or to any other party entitled thereto.