Jon:
The way I recall the Indian situation was that Wampanoag tribe had some control over the western half of the pond as it lies in Aquinah, their town. The eastern half was controlled by the town of Chilmark. Menemsha lies in the town of Chilmark. The harbormaster worked for Chilmark at the time. Back then they tried to discourage boats going up into the pond, mainly saying you couldn't because there wasn't enough depth in the channel. But I was never told by anyone to leave when I was up there. And there were always a few boats up there in the height of the season, so I was never alone. I don't really know what the situation is today but you can easily find out by calling the harbormaster or the Chilmark town offices and ask the questions.