First, your link to the map images is broken. All I get is an error 404. You should look into that.
Some of the statements you made about navigable-in-fact for commercial or recreational uses are not accurate. Read the controlling NY case then come back and we can talk.
BTW, any argument about avulsion or accretion are of no significances in your case. These are both natural phenomenon that chances the landscape and to argue them as a matter of law in your case is a red herring.