Cal. Streets and Highways Code § 1480.5

The road commissioner may immediately remove, or by notice may require the removal of, any of the following encroachments: (a) An encroachment which obstructs or prevents the use of a county highway by the public. (b) An encroachment which consists of refuse. (c) An encroachment which is a traffic hazard. (d) An encroachment which is an advertising sign or device of any description, unless excepted by subdivision (c) of Section 1460. The road commissioner may return such sign or device to its owner, or otherwise dispose of it in his discretion, except that if the commissioner determines in good faith that the sign or other device is of more than nominal value he shall not effect such other disposition until he has made a reasonable attempt to identify and notify the owner of the sign or device and provided a reasonable time for the owner to retrieve it under provisions of this section. The return of such sign or device to its owner may be conditioned upon payment of an amount sufficient to reimburse the road commissioner for the expense of removal. The road commissioner may recover from the person causing any of the above encroachments, in an action brought in the name of the county for that purpose, the court costs of the road commissioner, the expense of such removal, and any other damages caused by the encroachment.