Here is a great resource with multiple sections on what you're looking for.
MDHTALK - National: Where is it Legal to Metal Detect? by Lee Wiese
Treasure-diggr, interesting link. The page starts off with 100% federal stuff (arpa, etc...). And would thus only apply to fed. land, not other forms of land. As you go lower on the page, it has stuff about schools, parks, states, counties, etc.... and essentially, gives no answer, since ...... of course...... it would depend on which city, county, state, etc.... And even within those entities are various forms of land (ie.: not all state, county, or city land is "park" land, for instance). And it goes on to say that even though a place may not have anything on the subject (ie.: silent on the subject), yet any place could morph something else to apply (the dreaded alterations, digging, etc... verbage). So in essence, the link doesn't do much good for anything below the federal level, and someone would still have to (if they were skittish) find the rules/laws of lower level places.
Carla, the ONLY place I've heard of in your area of CA that had any bruhaha ever, was Stinson beach. And only because it's federal. All city and counties around you have no specific wording about detectors, to my knowledge. There's a club in Santa Rosa with some good fellows (last I heard the club was still active anyhow). They would know the real skinny on things of this sort. Also get on the Kinzli CA forum, and there's fellows chiming in there from around the SF area.
Oh, and back to Stinson fed beach, in the late '90s or early 2000s, a newbie in that area simply didn't know any better. Humorously he'd gotten his first detector, and took it to that beach. Imagine his surprise when he started getting targets hand-over-fist as fast as he could dig! It was as if the beach were virgin, and he just couldn't understand "why the locals weren't all over this". So he kept returning every day, week after week, and getting 100 to 200 coins, with ease, at-will, anytime he'd go. Also occasional rings in the mix. I started corresponding with this fellow back then, and got him to drop his guard and let me know wehre he was hunting. Imagine his surprise when I informed him that ...... I had heard, was off-limits. He simply couldn't believe it. Because he had gone every day, for several weeks, in full view of anyone and everyone, and no one had paid him any mind. Yup, in full view of life-guard towers, passing rangers, etc... Doh! Thus he thought it was
me who must be mistaken. Because certainly someone would have said something by now? haha He had half a mind just to continue since it was obvious no one cared. Not sure whether he did or not.
Along with the Federal Laws listed, which are required reading for anyone new to the hobby in my book, there is a wealth of info and links for laws at the State and City level including a searchable database. It also gives great suggestions and tips for someone new to the hobby on ways to search to find the laws and ordinances for their area.
