Film Permit requirements vary for cities, state parks, and highways.
A county film permit is required for the unincorporated areas, you can get more information on permit requirements for specific locations by contacting the Film Commission.
County Film Permit - http://www.co.mendocino.ca.us/econdev/Locations/permit.htm
Filming on State Parks - http://www.parks.ca.gov/?page_id=24777
California Film Commission - http://www.film.ca.gov/Production.htm
Film Liaisons In California Statewide - http://www.filmcalifornia.com/
Filming on California Roadways - http://www.film.ca.gov/LocationTools_CaRoadways.htm