infotraker, to answer your question : Yes, beach erosion hunting is venue of the hobby that many of us here study/try with a vengence and passion Once you've ever landed on a good erosion pocket, where you can dig 200 to 300 coins in an area no bigger than a basketball half court, you'll never return to dry sand hunting again
Is there something specific you wanted to know about beach erosion hunting in CA ? What part of CA are you in ?
And to answer your last question: All the beaches of CA are historically fair game, except ones that are federally administered. Fortunately, that's very few in/on the entire coast of CA. Most all are state, city, out county administered. And at all of those, you will be ignored. And to be honest with you, I even suspect that even at the federal ones you'd also be ignored, but .......... the technical answer to your question is: Fed only. I can only think of a certain small section that is fed. in all of CA. And that's the GGNRA portions around the mouth of SF bay. I don't know of any other fed. beaches in all of CA, but perhaps there's a few more. So essentially, the entire coast of CA is fair game.
Some of the military bases you need a military I.D. to get on base, but, once you do, you can usually hunt the beaches there too, unless it's a sensitive area. Those are usually posted.