Earth Matters Proper culverts critical for water and wildlife alike
Curtis Brook runs through an old metal culvert under a dirt road at the Steep Rock Preserve in Washington. The culvert might date back to the 19th century heyday of the Shepaug Valley Railroad.
The main problem with it is that one end sits at least 18 inches above the course of the brook. Brook trout migrating upstream from the Shepaug River might be able to make the jump and continue upstream. Wood turtles probably wouldn’t.
Rory Larson, conservation and program leader for the Steep Rock Association, said the Connecticut Audubon Society named the Shepaug River forest block an Important Bird Area, in part because it shelters the Louisiana waterthrush, a species in decline throughout North America. Waterthrushes like streams that run through woods. An old culvert, like the one carrying Curtis Brook, degrades the brook and, hence, the birds’ habitat.
“Cold water streams are part of the native habitat,” Larson said. “They’re incredibly valuable.”
The Shepaug is part of the 1,950-acre Housatonic River watershed. In it, streams and roads cross each other’s paths at least 6,000 times. That’s at least 6,000 bridges and culverts.
“We’ve looked at about 2,000 of these structures,” said Mike Jastremski, watershed conservation director for the Housatonic Valley Association. “About 60 percent had moderate to severe deficiencies. They’re definitely a risk to fish and wildlife and a flood risk as well.”
Jastremski and Larson were at the Curtis Brook culvert last week, along with HVA conservation manager Lindsay Keener-Eck and four HVA summer river stewards. They’re working to catalog culverts in five towns —Washington, Roxbury, Shelton, Oxford and Dover, N.Y.
In past summers, HVA has done the same in seven other Litchfield County towns, including Kent, Cornwall and Sharon. Grants from the Northwest Connecticut Community Foundation, the Connecticut Community Foundation and the National Fish and Wildlife Foundation helped pay for this work.
The HVA’s goal is to create a working database about culverts and the streams that cross them.
To do this, it’s collaborating with Manos Anagnostou, a professor of environmental engineering at the University of Connecticut, and the Connecticut Institute for Resilience and Climate Adaptation.
With the data HVA gathers and Anagnostou’s engineering expertise, the HVA wants to give towns plans to replace worn-out culverts with ones that will be environmentally sound as well as offering more capacity when big storms fill those streams to flood stage.
“We’re looking at multiple interventions in one study,” Jastremski said.
Such environmentally sound culverts might have more upfront costs, but they save a town money down the road in terms of flood repair and maintenance work.
“They’re not pulling stuff out of the culvert every year,” Jastremski said.
In the cold water streams of Litchfield County, they’re also better for brook trout moving up smaller brooks to spawn and to seek cooler waters in summer. To the south, in towns like Oxford and Seymour, properly designed culverts will let migrating species like eels and river herring move upstream freely as well.
A well-designed culvert also provides a safe under-the-road passageway for turtles, for mink and muskrat and raccoon.
“This is very anecdotal,” Jastremski said. “But I stop and look at roadkill when I can. It seems a lot of them are near culverts.”
The HVA program is also giving college students a chance to do real field work in between semesters, even if it means tromping around rocky stream beds in waders lugging surveying gear and iPads.
“I love this job,” said Kendra Beaver of Danbury, who is studying environmental and political science at Dickinson College in Carlisle, Penn. “It’s just what I wanted to do this summer.”
After finishing at Curtis Brook, the team moved on to study the effects of a new, much-improved culvert over Walker Brook. Washington First Selectman Mark Lyon said the town finished work on the new structure, which cost about $900,000, this spring.
The state Department of Energy and Environmental Protection helped design this new culvert, which replaced one in near collapse.
“The bottom was all rusted out,” Lyon said.
While it’s not perfect, Jastremski said, it’s a major improvement.
“We understand. This work is expensive,” he said. “You do the best you can with the resources you have.”
Then the team moved on. Keener-Eck laid out the plan to look at least at a couple more sites before lunch.
Then there’s Roxbury. And next summer to think about.
“It would be great if we could do this for every town in the Northwest Hills,” Jastremski said.
Contact Robert Miller at email@example.com