Re: California State Parks & Forest MD Rules
California State Parks prohibit the removal of all things, GENERALLY SPEAKING. This rule will vary, however, depending on who is on duty at any given time. Some rangers are more lenient and will let you hunt for modern coins. Historical and/or valuable items (modern items like Rollex Watches) are to be left in situ and reported to the ranger.
California State Beaches also have prohibitions against removing items. Again, it all depends on who you talk to when asking permission. The laws are quite explicit, but seem to be enforced in degrees and depending upon whom you speak with.
California State Forests are closed to prospecting, stream damage, rock removal, etc. They are less apt to be patrolled regularly by staff, but they are part of State lands and State lands are generally off limits to any type of real or perceived damage.
There is a State Park that permits gold panning, unfortunately I don't recall right now which park that is. One of the parks in the Mother Lode area.
And the 50 years old or older limit is true for most of the BLM lands. I have in my possession a brochure from a BLM office in Nevada that seems to indicate older items can be removed and MDing is allowed, but the brochure is somewhat vague.
The only sure way to know what, where and when you can metal detect, pan for gold, etc. is to go to the place and ask the ranger on duty. Calling on the phone almost always results in a firm "NO" when I used to do it. I now go to the place, ask politely and state what exactly I indend to do. At the local State beaches I have had no problems metal detecting the sandy areas, as long as I don't go near the dune grass.
Sorry, but there doesn't seem to be any hard and set rules about detecting or whatever on State lands. I do know for a fact, however, that on State lands you are not to damage, destroy, kill, injure, or in any way harm the vegetation and/or wildlife. Removal of rocks is even prohibited most times.
Fact is, for me anyhow, I avoid State lands when treasure hunting. Even the beaches are not that thrilling for me. Usually the coins are few and the rubberneckers are many. Of course, I am referring to the lack of coins at Northern California beaches, which get fewer swimmers and sunbathers than SoCal beaches.