The Nissitissit River runs southeast from Lake Potanipo in Brookline, and flows into the Nashua River.

There’s a lovely little swimming hole at Bohannon’s Bridge in Brookline, which might also make a good spot to put in a canoe or kayak, though I’ve not tried it.

The Nissitissit looks and smells to be the cleanest of all our local rivers. I'm sure it's no coincidence that the surrounding land is nicer, too. There aren’t so many houses close by the banks, and a good stretch of the river runs through conservation land in Pepperell.

Though the road crossings are never a problem, there are some substantial downed trees along the Nissitissit. It’s tricky, but with most of them you can climb onto the trunk, and haul your boat over it.

There’s also a dam in Pepperell, Mass., that can’t be portaged without stepping onto private property, so I can’t really recommend running it. Unofficially, it’s a great trip. The river is mostly flat water, with a few speedier riffles here and there.

I’ve run the Nissitissit from the Beaver Brook trailhead (at the west end of Worcester Road) in Hollis down to the Nashua River.

There’s also a nice put-in/take out spot behind Shattuck Oil in Pepperell, Mass., which has the advantage of being below that dam. The Nissitissit runs pretty shallow from there to the Nashua River, but I don’t know of any place to get a boat into the Nashua in that area, between the Pepperell Dam and Hollis Depot (Route 111 and Depot Road).