Fish & Fisheries

Where the River Meets the Road: Reconnecting Adirondack Brook Trout Streams

The brook trout is the jewel of streams in the eastern United States. Photo: Lisa Godfrey

By Matt Miller, senior science writer

As you drive around the Adirondacks—enjoying the jaw-dropping scenery—you can be forgiven if you don’t notice road culverts.

From a car, it might look as if you’re passing over a small bridge. Underneath, though, is often a metal tube channeling water—a tube that may create a barrier for native fish. While these culverts may escape your attention, for fish they are a matter of life and death.

That’s why the Conservancy is working with the New York State Department of Transportation and local highway departments to provide better fish access through culverts – a step that may help tangibly address some of our most pressing conservation challenges.

Relatively simple fixes in culvert design could reconnect miles of habitat for brook trout, one of the most iconic fishes of eastern streams, and prevent flooding during severe storms.

“Culverts may not be sexy,” says Michelle Brown, conservation scientist for The Nature Conservancy’s Adirondacks Chapter. “But improving them is a concrete step we can take to address climate change and connectivity for native fish.”

Jewel of the Forest Stream

Flyfishing for brook trout draws many anglers to Adirondack waters like the Ausable River.
Flyfishing for brook trout draws many anglers to Adirondack waters like the Ausable River.

Brook trout hold a special place in anglers’ hearts: they’re the native trout of eastern streams, colorful and beautiful. It doesn’t hurt that they’re often found in almost impossibly picturesque places: crystal-clear bubbling creeks flowing through piney forests.

Brook trout need cold, clean water. And in their native range, they’ve been hit hard by the horsemen of the fish apocalypse: non-native species introductions, pollution, acid rain, deforestation, climate change.

In some ways, that has made them even more cherished by anglers and conservationists, who consider them not only quarry but an indicator of ecological health. The angling literature is full of purple prose celebrating the dwindling brook trout, but perhaps no one put their ephemeral nature better than Cormac McCarthy in his apocalyptic novel The Road:

“Once there were brook trout in the streams in the mountains. You could see them standing in the amber current where the white edges of their fins wimpled softly in the flow. They smelled of moss in your hand. Polished and muscular and torsional. On their backs were vermiculate patterns that were maps of the world in its becoming. Maps and mazes. Of a thing which could not be put back. Not be made right again. In the deep glens where they lived all things were older than man and they hummed of mystery.”

Except, in some places, brook trout streams can be made right again. And perhaps nowhere is that more true than in the Adirondacks, the six-million-acre state protected area in northern New York.

The Adirondacks still have the extensive forest habitat and clear streams for brook trout to survive and thrive. Many streams have what fisheries biologists call heritage-strain brook trout—trout strains that have not been altered by stocking, fish perfectly adapted to specific watersheds, specific streams.

“Brook trout have been here since glaciation,” says Brown. “They’re a major draw for visitors to this area, helping to feed our economy. But even here, brook trout face challenges.”

Chief among those challenges is climate change. Brook trout need cold water. Period. As rivers warm, they need to move upstream into small headwater streams in the mountains, what Brown calls cold-water refugia.

Right now, their route to those cold waters is often blocked – by road culverts.

Improving Roads for Fish and People

A poorly designed road culvert for fish. Note that the pipe is above the stream, essentially cutting it off for native fish. Photo: Ausable River Association
A poorly designed road culvert for fish. Note that the pipe is above the stream, essentially cutting it off for native fish. Photo: Ausable River Association

There are 1.2 million culverts on New York State roads and at least as many on town and county roads. Obviously, changing all of them for fish is not feasible.

Fortunately, Conservancy scientists have mapped where culvert modification can reconnect streams for brook trout and other fish species.

The maps pinpoint places where conservationists can make the most difference. Scientists look for places with good fish habitat that native species could easily reach by modifying road culverts. For instance, some culverts are higher than the stream, creating what is essentially an impassable waterfall.

“We look for culverts that are blocking the most stream miles,” says Brown. “For example, there are places where removing one culvert opens up 10 miles of habitat. That is a lot of stream for brook trout to use.”

Brown believes that in some instances, like the world-famous fishery of the Ausable River, it will be possible to connect the entire watershed. “That could really help brook trout adapt to climate change while at the same time helping the local economy,” says Brown.

Of course, removing or modifying road culverts costs money, and funding for highway maintenance is often tight. How do conservationists convince highway departments to help with projects that benefit fish?

Fortunately, these projects are important for people, too. Scientists are focusing on culverts that can be modified cost effectively, but they also are looking at roads that flood frequently – causing hazards or closures for motorists.

“As we saw with Hurricane Irene, natural disasters are a huge deal for roads,” says Brown. “By improving culverts, we can save money on highway maintenance while also helping fish populations.”

The key to success is working with people who know the highways best, like county road supervisors. “They know where the road floods when it rains,” says Brown. “There are road supervisors who put up cones before a storm, because they know it’s going to flood. These are places where we can make a real difference.”

A well-designed road culvert. This will allow fish to pass and reduce the likelihood of flooding. Photo: U.S. Forest Service, Green Mountain National Forest
A well-designed road culvert. This will allow fish to pass and reduce the likelihood of flooding. Photo: U.S. Forest Service, Green Mountain National Forest

The Adirondacks is one of the oldest protected areas in the world, a fact that has made it easier to deal with many conservation challenges, from invasive species to landscape connectivity. Improving culverts may be one way to deal with the often-daunting prospects of climate change.

“Climate change can be so hard to get your head around,” says Brown. “What can we do to make a difference? Here is one thing. We can map culverts and upgrade ones that make sense for people, roads and fish. By doing so, we’re connecting whole watersheds and providing a native fish with a refuge. It’s a concrete step in facing a global challenge.”

Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.

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  1. Great article. Culverts or any other type of under road, railroad bed, trail etc. sure can have a major impact on fish all over the world. Idaho work on redband trout and other fish species safe passage is critical to their survival in many places. Thanks for highlighting it.

  2. Ken,
    Thanks for the comment. Yes, I know passage through culverts is important for redband trout as well as Yellowstone cutthroats in Idaho. I have also seen how culverts can influence northern pike moving out of the Great Lakes and for a wide range of fish species in Florida. Like you said, it’s an issue all over the country. Fortunately, this is one conservation issue where there is an easy fix!

  3. I spotted this article way late, but since it appears to be open yet, and culvert/ fish passage issues in coastal Oregon salmon streams is an evolving technology that does not get enough critical thought at times for ecotoxicology, I’ll comment anyway.
    Metal culverts and poorly buffered waters don’t mix well.
    Galvanized pipe may be a significant pollution source to cool water refuge sites associated with culverts at road crossings. Usually, the mainstem streams can have temperature limited issues that are often helped by cooler water input by tributary streams. Often, these locations create cool water refugia for heat stressed fish.The trib water chemistry, if on the lower end of the acid neutralizing capacity scale, can be subject to episodic buffering challenge event dips in pH and calcium carbonate availability. If the dips are low enough, say during copious rain and snowmelt events, even aluminized culvert material might be dissolving to expose the biota to toxic metal influence spikes. At least heavy rains, and snowmelt would not be as likely to happen at peak temperature refugia periods.
    I have not found research lit that sufficiently clarifies these potential risks. If concrete based arch style passage can be designed and utilized for metal culvert replacement, there may be much safer passage created.

  4. Its good to see this getting addressed. When they build roads they don’t usually have much foresight into how it could effect a small stream brook trout population. Many of the streams are small enough to jump over and could likely pass for a ditch to the untrained eye. As much regulation as there is for some things it is hard to believe they left the little brookies high and dry in the first place. A huge win for the brook trout for sure.