Here is where I’ve fished:
PRESCOTT STREET BRIDGE (map coordinates)
It’s fly fishing only from the bridge to the MA/NH border. When I was there, it was full of anglers and no one was catching. There’s some deep water below the bridge at Prescott St. I’ve not witnessed any hatches when I’ve been there, but I can say that some of the water there seems to beg for a streamer. Or, I’d check out this area during a hatch or spinner fall.
GOSSELIN DRIVE (map coordinates)
This is a residential area, but there’s a path to the river near there. This stretch of the river is quiet and has a great deal of woody debris in the water. I’m guessing that some good-sized brown trout hang out there. It’s a bit creepy to park at a residential area and rig up. I felt like a stalker.
SHATTUCK OIL (map coordinates)
This is a stocking point, and, if you get there early, you should be able to beat the crowds. Last time I was there, the fish were pooled off the near bank, under the bridge. Access is easy and that spot would be ideal for teaching children how to nymph. The one Nissi trout I hooked was there and it was huge. Unfortunately, it popped off. There’s also some quick water below the bridge, and that’s a likely spot to indicator nymph, as trout have to decide quickly if they’re taking a nymph.
Also, note that Gulf Brook, a tributary, has a wild brookie population. It feeds into the Nissitissit in a spot on the NH side.