Hi, I just joined, and couldn't help but notice this thread. The Swift River is probably the best fly fishing for trophy rainbows in Massachusetts, and although the trout are picky, it's not as hard to catch them as advertised. Terrestrials are unbeatable in the summer, but all sorts of other patterns work.
For me, my best all around Swift Fly is a soft hackle. The Millers River Fly Fishing Forum has a few other good flies. But the best way to catch the biggest trout in the stretch you're fishing is to throw a mouse! A deer hair or foam mouse with a long tail will absolutely produce fish if you fish it at dusk in the calmest water you can find. I've caught up to ten fish and hour using this technique at about 9:00 PM. Cast near the shore and strip it across the river. The explosions are incredible! this works in the Y Pool too.
Awsome. Enjoyed reading this
As far as other rivers nearby, the Quaboag (as mentioned earlier) is pretty good, and I've had success throwing streamers there. The Quinapoxet is pretty good if you enjoy fishing for small stream trout, and near it is Fish Brook, which also holds some trout.