Everything is on the photographer, unless the client has made arrangements/agreement with the location.

Keep in mind that any commercial involvement in photography at the location will required a permit AND insurance naming the said location in the liability coverage.

When I used to live and work in the Los Angeles area, almost any location requires a permit and insurance. LA is LA afterall. Having said that, most like to try the "guerilla method." This is where everyone takes the risk of being stopped by the police/ranger and have the shoot canceled.

You can try being a "student" and what you're doing is for a "school assignment/project." This will only works, if you have an old student ID. Any police/ranger will ask the photographer who is conducting the photography.

If you're trying out the guerilla and/or student method, don't carry large lights. Use a small stroke and reflectors. If you start setting up octaboxes or more, you are being asked for attention and the police/ranger will definitely stop you and you have ruined your photo session and does not look well for you (if that happens) in front of your paying clients.