controlfreq, I fear that any answer you may get to your question, will be the type answers culled from decades of people asking bureaucrats, and answers given back because ........ doh ..... they asked. I mean for example: "lost & found" laws apply in every state, that's nothing new. But a simple look at any beach hunters finds forum shows you ample of us hobbyists find rings and such all the time, right? Do you really think they're all rushing down the police lost & found to turn them in? Those laws were born out of wandering cattle laws in the 1800s, and certainly can be used to prohibit someone who scoops up wads when a Brinks armored car door swings open, from saying "finders keepers". So .... yeah, I suppose if you asked long enough and hard enough, of enough lawyers and bureucrats, sure, it applies to your "pressing question" too.
Other such answers like cultural heritage things (can't keep items over 50 yrs. old), also predate metal detecting. I mean, sure, does anyone really think we can raid historic monument for our own fun and profit? And sure, arbitrary date/age cutoffs are given, way back when these laws were enacted (as I say, before detectors came about). And sure, if you ask long enough and hard enough, someone will say you can't keep the 1959 memorial penny you just found. But ........ did anyone really care less? (till you asked?). I mean, c'mon.
Or the dreaded "alterations" "digging" and "defacement" verbage. Those too are age-old verbage so no one thinks they can go to the beach and start harvesting the sand, or removing trees and swingsets, blah blah blah. But could they apply to digging a small divot for a coin? SURE (if you ask long enough and hard enough). So too could they be applied to say "no", if you ask enough bureaucrats if your 6 yr. old daughter can pick up seashells on the beach too. But again, did anyone really care if your 6 yr. old daughter picked up the seashell? No, of course not.
So the bottom line is, whenever a question like yours comes up: "Is it legal to detect in such & such place", someone else will invariably come on with a variety of "no" type answers, all of which were borne out of the seemingly innocent method of asking. And you know what the easy answer is.
There is a particular federal beach in CA, where rumor had it, amongst md'rs, dating back to the 1970s, that it was "off limits". No doubt, info that gets fed into the network of md'rs over the years, starting from way-back-when when someone asked "can I?" The odd thing is, that after decades, it's just simply taken as fact, in the md'ing community (afterall, if you look long enough and hard enough, i'm sure there's cultural heritage things you can find in the verbage, or perhaps an isolated booting decades ago, etc....). Then one day, a beginner md'r, who simply didn't know any better, went to detect that beach. Imagine his delight when he found the sands to be practically virgin! Hundreds of coins per day, as fast as he could dig (and a sprinkling of jewelry some days too). He simply couldn't understand why the "locals weren't all over this". Eventually, he began to make friends and meet others in the hobby. One of them, upon hearing where he was md'ing, told him "but I thought that was illegal to detect there". The beginner md'r simply couldn't believe it. He had been there for weeks-on-end, in full view of anyone and every (yup, right in front manned lifeguard towers, etc...) and no one cared less! Even after hearing from this long-time md'r, the newbie had half a mind to just continue, as it was painfully apparent that no one cared. Moral of the story?
All I'm trying to say is, take the answers you will get, to such a question as yours, into context. Because you/we can always find ourselves a "no", if you ask enough people far enough up the ladder, with enough key buzzwords. Not saying some places are truly enforced or truly care. Perhaps some do (obvious historic landmarks, obvious wrecks under lease, etc...).
(If the price of pull tabs ever spikes, I'm retiring.)
