Spent most of yesterday researching this and WA has lots of grey were this is concerned. As per the public trust doctrine, to me the tidelands can be owned to the extreme low water mark based on the year of the sale. High water in other cases. But when the tide comes in you are now using navigable waters, and from the sounds of the public trust doctrine, anchoring would be okay.
Buddy was hunting a spot I hunted the day before and the owner came over and yelled at him he was trespassing, fortunately he just finished filling his limit while this guy who also was hunting fired one or two shots. Guy claimed he owned out 500 yds into the tidelands which were under 8 feet of water at the time. I checked the accessors maps and he is not the legal owner of the tidelands off his property. The name my buddy gave me matched the owner of the land but not the tideland parcels.
Will be checking with another friend a retired attorney who used to be a property attorney, so hopefully will have more skinny. Right now after doing all the reading it sounds pretty unenforceable. I had a great shoot with my nephew and plan on returning to that spot again, Will be armed with maps and names and hopefully a few statutes as well. Just in case.
Read pg 27 of the public trust doctrine or better yet read the whole thing, 74 pages. WA has not made a decision, one way or the other, but from my interpretation, any thing above the tidelands is good, and you have the ability to fish our fowl.