And because it annoys me, the above statement is false. Only some cases do a property line extend into the water and still that doesn't dictate ownership of the body of water itself. Many a property line go to MHW (mean high water) or shoreline and it is a false assumption they extend beyond into the body of water. In those cases riparian rights are invoked. Riparian rights and property ownership are two different things, this is where you get lost on most of my posts regarding the subject. Stasher had the best post with demostrating the ownership/access of the body of water, USACE, and the rights the owners had to the water. This is my point, look to the owner of the water for the guidelines on use and access. As it will be owned and maintained by the state, federal or a HOA institution. Many states and jurisdictions allow the construction of docks with a general permit, they also reserve the right to remove or modify such structures if deemed necessary. Now what you have stated holds some truths, but also holds some misinformation and common assumptions. Property law is very complicated and dealing with waterways etc. should best be left to a professional land surveyor. That is why you should seek the legal documents describing the ownership/access as I and Long Mike stated.