So I was watching the Rebel Gold TV Show and these guys came across a pit just like yours, at the Dan River Plantation in Danville, NC. They called it an "ice house" from the 1800's.
That's amazing how clear the water is... it must be fresh spring water. Hopefully, if it's truly an old cistern, then you can drain it, and look in the bottom for stuff people threw in there.
MAN... I wish I could air-lift the little bulldozer I use for treasure hunting to the Boston area and we could start pushing everything out of the way!
Maps have you ever Metal Detected this place. I would be all over it, I would start right up against the old structure, and work out in 360 degrees. Then I would be going wide looking for wagon trails and foot trails. You might score some 100 plus year old coins. There could have been old log cabins at this site that are long gone now. Maybe it was a water source for steam engines.