I agree, the only reasonable path forward is to next look at those land deeds. I have done this online in several towns and have found both public domain watercourses and ponds and private deeded watercourses and ponds. So who is going to town hall? I would go just out of curiosity but I live at a great distance. Step lightly if you do, some politically connected landowners have considerable local political clout, we want a state government ruling, not a town ruling or opinion.