Yes, the quarry pit. Is that the same reservoir you said has all those jumbo BG that the locals despise?
The locals don't consider "sunfish" worthy of their time pretty much anywhere in the state. A ten inch stocked trout gets more attention than a 10 inch bluegill. You have to see it to believe it.
Area three in Quabbin is the place to go for the bluegills. That arm of the reservoir is more fertile and shallower than the other parts of the reservoir that are known for lake trout and landlocked salmon.
One interesting thing though. I've caught bluegills up to 11 inches in Mass but they are not as thick as our fish here in Indiana. My theory is these are older slower growing fish in low fertility waters that are mostly unmolested.
