I don't know where this idea came from, but I do know it is not correct. Go to the Fema website and find a firm map for the area around any given river and you will see the shaded areas that are Zone A (commonly known as the 100 year flood hazard zone). These flood hazard zones usually encompass most of the woods and fields along a river, often stretching for miles and it is not too unusual to see houses in the flood hazard zones as well. Also many counties have GIS sites where you can click on a layer to shade and expose the flood hazard zones, but I am positive that there is no law that makes these flood hazaed zones open to the public. I believe the arguement could be made and won that when a navigable waterway is low enough to expose sand bars you could legally dock your boat and hunt these sand bars, but as 10point pointed out, once you leave the water far enough to enter upon the areas covered by normal vegitation you are on property owned and controlled by private individuals, not the State.