I just pulled this off of the California OHV website
http://www.ohv.parks.ca.gov/default.asp?page_id=1234
SPEED, TURNING, RECKLESS DRIVING
You may not drive a motor vehicle in a manner that endangers the safety of other persons or their property (CVC 38305, 38314, 38316a, 38317).
PRIMA FACIE SPEED LIMIT
No motor vehicle shall exceed 15 mph within 50 feet of any campground, campsite, or concentration of people or animals (CVC 38310).