California Code, Streets and Highways Code - SHC § 225

(a) The department may enact rules and regulations governing the time and manner of use of safety roadside rests, and all state laws and rules and regulations of the department shall be administered and enforced within the safety roadside rests by all employees of the state authorized by the department to do so and by all peace officers.

(b) No person shall engage in any activity within a safety roadside rest area or vista point prohibited by rules and regulations adopted pursuant to this section.

(c) A violation of subdivision (b) is an infraction.  A second or subsequent conviction of a violation of subdivision (b) is a misdemeanor.