This summer the Ausable Freshwater Center (AFC) finished a stream restoration at the Moss Road crossing of the North Branch Boquet River in the Town of Lewis, in Essex County, NY, by removing two old, undersized culverts to restore a natural river channel.
The culverts that had constricted the river and blocked fish for decades are now gone, and a natural channel carries the river through the road crossing. The project reconnected some 50 miles of Adirondack river and coldwater tributary habitat.
The Essex County Department of Public Works’s Division of roads and Bridges (DPW) was tasked with placing a new bridge.
The project is part of overall regional efforts to restore and protect the Boquet River watershed. These have included removal of the former Willsboro Dam in 2015 to open more than 30 miles of the lower river to species such as landlocked Atlantic salmon and American eel.
The Old Crossing
The Moss Road crossing was a dual-barrel culvert with a combined opening of about 32 feet, which forced the river when bankfull to a width of about 50 feet through a gap far too small. The culvert outlet sat above the streambed, creating a drop to the water below that fish couldn’t clear at lower flows.
A sheet-pile wall above the culvert entrance added a second barrier. Debris often blocked the barrel openings, water pouring from the outlets scoured the channel just downstream. The resultant flooding became a public-safety issue.
This stretch of the North Branch Boquet is exceptional coldwater habitat. Biological surveys regularly find landlocked Atlantic salmon and native brook trout and opening the barrier also lets the river naturally move sediment through the crossing.
A 2024 freshwater mussel survey by Biodrawversity turned-up more some 5,700 eastern pearlshell mussels in the reach up and downstream of the crossing, with large concentrations near the project site.
The eastern pearlshell (Margaritifera margaritifera) is a long-lived, pollution-sensitive freshwater mussel that is a species of conservation concern in New York State; it lives in clean, cold, well-connected water.
“In other words, the very mussels complicating the project were themselves proof of exactly the kind of river we were working to protect,” a recent announcement by AFC said.
Rather than attempt to work around thousands of rare mussels, AFC, in coordination with the New York State Department of Environmental Conservation (DEC) and US Fish and Wildlife Service (FWS), and under a state License to Collect or Possess, Biodrawversity salvaged over 2,400 mussels from the work zone and relocated them by hand to suitable habitat a safe distance upstream, each one re-bedded in its natural position.
“And when the culverts finally came out in early July, a DEC biologist was on-site to check the streambed beneath them,” AFC said. “Seven live mussels found under the northern pipe were carried upstream to join the rest.”
A New Smaller Footprint Crossing
The mussels reshaped the effort, project organizers said. The original concept called for extensive bank stabilization and three grade-control structures. To avoid disturbing the mussel bed any more than necessary, they scaled back the in-stream work.
Instead, they reconstructed a natural channel through the new crossing with small floodplain benches on each side, protected the toe of the new streambanks with rounded, native boulders, and installed two channel-spanning converging rock clusters to hold the design slope and prevent the river from scouring the bed through the new crossing. The redesign shrank the streambed disturbance to less than 60 linear feet they said.
“None of this was guesswork,” AFC told supporters. “Before the design took shape, AFC conducted a geomorphic assessment on over one-half mile of the channel, interpreting dominant geomorphic processes, mapping bed forms and sediment, and carefully measuring bankfull dimensions.
“We also used a hydraulic model to better understand the stress exerted on the bed and banks during floods and to assess the changes in flooding from removing the bottleneck imposed by the existing undersized culvert.
“Staff at the USFWS Partners for Fish and Wildlife Program in New York helped refine our design and developed a plan set to guide construction.”
That effort mattered because the river here gathers runoff from about 44 square miles of the surrounding mountains, and upstream of the crossing its valley bottom is filled with fine sands, gravels, and clays left behind by an ancient glacial lake, which drowned these bottomlands at the end of the last Ice Age.
“That material unravels quickly once a river starts cutting down into it,” AFC said. “The two rock clusters installed do quiet but essential work to prevent that tendency: they lock in the channel’s elevation, keeping a headcut from marching upstream through those erodible glacial deposits and, just as importantly, keeping the streambed from scouring out beneath the new bridge’s foundations.”
The culvert removal and in-stream construction were carried out by JB’s Excavation Services with AFC and FWS providing oversight.
With the channel complete, Essex County DPW is installing a new bridge design developed by SRA Engineers. AFC will seed and plant the disturbed areas with a native grass-and-wildflower mix and live-staked shrubs and trees. The rock clusters and benches are designed to be self-sustaining, with no ongoing maintenance expected.
“The river will take it from here,” says AFC. “As flow settles into the new channel and salmon and brook trout freely move into upstream habitat, the North Branch Boquet gets to go back to doing what rivers do best — moving water, sediment, and life through the watershed.
The Ausable Freshwater Center (AFC), formerly known as the Ausable River Association (AsRA), is headquartered in Wilmington, NY, and dedicated to advancing the science and stewardship of Adirondack waters, lakes, and watersheds. Sign-up for their e-newsletter to get their weekly updates.
Read More about New York’s Rivers and Streams
Illustrations, from above: Before and after images of the Moss Road crossing, looking downstream (provided by AFC); a cluster of eastern pearlshell (Margaritifera margaritifera) in the North Branch Boquet River, 2024 (photo by Ethan Nedeau of Biodrawversity); and the reconstructed channel, looking upstream (AFC).
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