If the pond that you are writing about spreads out over two separate parcels, one you own and the other that you do not own, you have the legal right to keep people off of your land, or the water over your land subject to the following provisos:1. the pond is not deemed a navigable waterway under state law and is not part of the public domain;2. your neighbors do not have an easement to use the water over your land.I suggest that you consult further with a real estate attorney about your situation.