California Code, Streets and Highways Code - SHC § 224

It shall be unlawful for any person to throw or deposit any substance in a safety roadside rest other than in a receptacle provided for that purpose.  It shall be unlawful for any person to deposit in the receptacles provided for refuse in a safety roadside rest any refuse or waste from homes, farms, or commercial establishments, or other material which does not arise out of the use of the safety roadside rest by a member of the traveling public.  The violation of this section shall be a misdemeanor punishable as provided in Section 42002 of the Vehicle Code, and all of the provisions of Chapter 2 (commencing at Section 40300) of Division 17 of the Vehicle Code shall apply to an offense committed under this section the same as if such offense were made an offense by the Vehicle Code.