LAKE PLACID – It’s a way of rethinking culverts that could benefit everyone involved, including fish.
This summer, a portion of River Road in Lake Placid has been closed to accommodate work crews who have been busy replacing a culvert there.
The old, steel tube that once carried water from one side of the road to the other is gone. Now Roaring Brook has a wide path to follow as it courses beneath the asphalt.
The project satisfies the interests of a number of stakeholders, including local municipalities, watershed steward groups, wildlife biologists, road maintenance crews and nearby homeowners. The Roaring Brook culvert is one of three projects this summer. There are two being replaced on River Road and one in Wilmington.
The Adirondack Chapter of The Nature Conservancy’s Jessie Levine explained that the new structure is almost three times as wide as its predecessor, which was 12 feet. TNC started looking at culverts in the region just before Tropical Storm Irene hit. Irene briefly but radically swelled streams and rivers, overwhelming roads.
“During a large rainstorm, the stream would get so high it would pass over the culverts and the road,” Levine said. “Instead we’re letting the stream be a stream through the culvert. It allows fish to move. It allows sediment to move, like large rocks. It allows woody debris to move through. The smaller culverts would clog.”
Levine said the wider culverts cost more, but they also last longer than their tube-shaped counterparts: 100 years versus 25 years. They also require less maintenance, which saves money over time.
Dave Reckahn, Essex County Soil and Water Conservation District manager, said the new culvert will take a burden off of maintenance crews having to unclog drains after storms.
“The long-term effects are, the people who drive this road daily don’t have to worry about every little storm that comes up, whether it’ll overtop the culvert or get plugged in the winter with ice,” Reckahn said. “That’s why the extra time and effort in going through this is worth it for the DPW (county Department of Public Works) and other municipalities.”
A lot of culverts were destroyed during floods caused by Irene. Reckahn said many of those were replaced with tubes similar to the ones that failed.
“FEMA (the Federal Emergency Management Agency) only gives money to replace what was there, unless the county has an ordinance that says anything that’s replaced has to be upgraded,” Reckahn said. “The only problem is, once you pass that ordinance, you have to upgrade every culvert, and they’re not ready to do that.”
More recently, Reckahn went to each culvert site in the county with workers from the DPW and tried to match that agency’s priorities with the ecological priorities of the Ausable River Association.
From there, a list of priority culverts was created that met the needs of humans and non-humans alike.
Madeleine Lyttle, fish passage expert with the U.S. Fish and Wildlife Service, explained that the old-style tube culverts make waterways impassable for fish. The FWS has been working on upgrading culverts for nine years.
Levine said the area’s big rivers are getting warmer, and that means brook trout need access to colder tributaries. But culverts often block the way of those.
“Last summer we measured temperatures of almost 70 degrees in the AuSable, but this tributary was 10 degrees colder,” Levine said. “We just opened up 6 more miles of stream habitat.”
The exit point of a culvert is often much higher than the stream it’s flowing into, which creates a step that’s too high for brook trout, which can jump 8 to 12 inches.
Deeper water can close that gap, but that creates another problem. Since the tunnel is narrower than the stream, increased water flow also increases the pressure. It’s the same as putting your thumb over the end of a hose.
A natural stream bottom, like the one in the new culvert, contains countless little waterfalls, which fall from deep little pools along the natural grade. Fish can “hop” from one pool to the next to make their way upstream.
Fish aren’t the only things that move in a stream. Storms cause rocks to move, and they can accumulate at the opening of a tube culvert, creating blockage that water flows over.
“With those old tubes, logic-wise, the idea was the only thing you had to get across the road was water, and that’s not a stream at all,” Lyttle said. “Everything moves. The bottom moves. If you make it big enough so the stream is a stream, it will adjust itself to the conditions, and that’s all we’re talking about. These bottomless culverts are like rivers. They’re perfect.”
A short drive along River Road from the nearly completed culvert is another problem. Standing on the bridge over Holcomb Pond Brook, TNC conservation scientist Michelle Brown explained the new logic that’s being employed.
Even though the stream was only a couple of feet wide, it was easy to see the bank flow width – the maximum width of the waterway every couple of years – because the forest abruptly ends, giving way to a carpet of stones.
“We size these structures to 1.25 bank flows, so we want to make sure we’re well beyond what that annual flow is,” Brown said. “That way, when you do get a 50-year or 100-year storm, there’s room for the water to go.”
The new culvert will reflect that math. Holcomb Pond Brook’s bank flow is about 15 feet wide, so the new culvert will be 20 feet wide. It’s replacing a 6-foot-diameter pipe.
Brown has worked on culverts with TNC since 2007. The first project was with the state Department of Transportation, looking at state roads that fragment wildlife habitat. A couple of years later, her focus narrowed to the Champlain Valley and the Adirondacks.
TNC partnered with local municipalities, the county Department of Public Works, Essex County Soil and Water Conservation District and the Ausable River Association to determine where new culverts were most needed.
Shortly after their work began, Irene brought major flooding and damage to the region.
“Out of that terrible event came strengthened partnerships to work on climate adaptations that benefit lots of different stakeholders,” Brown said. “Our general goal is, we’d love to see these types of culverts become business as usual.”