Arrownoob's Link
Kidding aside, a lot of these old pieces actually are owned by out of staters who inherited them and have no idea what they have. If posted it's for legal purposes only and they don't enforce it.
If you click on a piece of property in MIPS, you can see the last sale date in the window that opens.
If you are unsure where to go, you may still be able to google up electro shocking data on coldwater fisheries in MA via Mass Wildlife. Last I looked it was hard to find but it's out there. This list lays out every water found to be able to support wild brookies in MA. Some are 2 foot wide trickles with a very low number of 2 inch long fish... others are quite surprising... But it can help.
Another strategy is to use a geology map. ARC GIS and a few other fed/state services have these you can look at. The trick is to look for areas where aqueducts are close to the surface AND there is sand, and ideally Carbonate, Calcpelite, and Calcgranofels rock formations near/around the aqueducts you are looking at.
Those rock types help shift acidity of the ground water which seeps into small streams toward neutral or basic. And the sand facilitates those sources of ground water reaching the surface to "charge" the streams with water through the year.
Brookies are relatively acid tolerant among the cold water salmonids we have here in New England, given they often live in beaver flows and boggy meanders or the streams which go through such places. BUT, the food they enjoy, the insects that really help them grow fast as youngsters, do NOT like acidic waters as much as neutral and basic waters. So, if you find a stream which is likely fed by more basic waters, it's likely a stream with much more food for the fish, and thus, likely a higher number per river mile and a faster growth rate to boot.
If you want to find a hidden gem small stream to go catch (and release) a mess of brook trout... That series of tricks can be REALLY useful!