The Upper Mattabesset is often overlooked but offers a nice run in the spring with a mix of flatwater and quickwater. Before running the river, check the gauge at the Berlin Street Dam - gauge should read 1.6 at that point and the rocks below the dam should be well covered with water.
Launching from France Street in Berlin, the river cuts through a blowdown area - watch for downed trees, then through a large farm, offering good scenery for such a developed area. After the farm, the river enters a long section of flatwater, crosses under Route 9 and approaches the Berlin Street Dam. Take out well above the dam on the left bank. Portage through the field. You could also launch below the dam.
After the dam, the river quickens and twists through a ravine area and under some old RR bridges before a long quickwater straight run. A short drop occurs near the Route 372 bridge (you can see the rapid from the bridge).
After the bridge there is another launch spot at an old bridge (behind Wal-Mart) and another small rapid. The river twists again through unspoiled woodland, passes under I-91 and drops again at an old trolley bridge. From there spring floods back up the CT river to create flatwater. If the CT river is low, the section below the trolley bridge can be shallow.
The river continues through floodplain forest with abundant bird life, crosses under Route 3 and continues to the CT river. Take out at Dunkin Donuts on Route 3, a small launch is maintained here - the Sawmill Pub has been demolished. Or continue another two hours though scenic floodplain forest and marsh areas to the CT River. The upper run is approx. 2 hrs.
Launch on France Street below the old dam.
The Mattabesset River Watershed Council has further information: