'Climate-Ready' Great Bay Culvert Shows Possibility, Challenge of Coastal Resilience

Sep 25, 2019

New Hampshire’s coastal towns are beginning to think about adapting to climate change. It’ll mean finding new ways to protect critical pieces of infrastructure from rising seas, heavier rains and stronger storms.

NHPR’s Annie Ropeik has this story of the lessons from a major road project in Newmarket that’s one of the first in the state to focus on climate resilience.


There's a back road in Newmarket where Rick Malasky has spent a lot of time in his 30 years as the town’s public works director.

The road runs over a squashed little pipe that’s supposed to let a stream flow through – connecting the Great Bay salt marsh on one side of the road to the woods on the other. 

That little pipe is a kind of culvert. Malasky, on a recent tour of the site, says it's been flooding more and more.

“It happens every year at some point,” he says. “Sometimes it would only be an inch of water going over the road, but it would just wash the shoulder out a little bit.”

Other times, it’s more serious – the stream swells enough to overwhelm the culvert and blow out the road bed, requiring detours and repaving.

And the effects of climate change are making the problem worse. State data shows that rising seas are causing higher high tides and pushing groundwater inland, creating new ponds that are primed to flood in heavier rainstorms.

A car travels through mild flooding at the site of the culvert project. in this file photo.
Credit Joanne Glode / Nature Conservancy

“It’s more frequent, more washouts, more everything when it comes to the weather events and the rains,” Malasky says. “There’s definitely stuff going on.”

Further reading: N.H. Coastal Flood Risk Summary, UNH, 2019

The town of Newmarket has spent tens of thousands of dollars repairing damage at the site over the years, and more in federal aid after major floods in 2006 and 2007.

They've known all along they need a long-term fix. The culvert is also on an evacuation route, one of the only ways out of town when the main throughway, Route 108, floods.

But the upgrade would be expensive, and Malasky says the town could never prioritize it. 

It turns out, they weren't the only ones who were interested. 

A model project

"So I seriously doubt there's another conservation organization on the planet that loves talking about culverts as much as the Nature Conservancy," said Mark Zankel, the state director for the nonprofit, at the recent site tour in Newmarket.  

The group’s Great Bay office happens to be right next to the town’s troublesome culvert. Years ago, Zankel's staff was testing some cameras in the creek there, when they noticed something at the mouth of the culvert. 

"There were dozens and dozens, maybe hundreds of baby American eels that were just bumping up,” Zankel says. “They actually got here all the way from the Sargasso Sea down near the Bermuda triangle, reached Great Bay, are swimming upstream to try to get to their historic freshwater grounds, and they reached this culvert." 

The original culvert on Bay Road in Newmarket was "perched" above the usual water level, preventing fish from traveling through.
Credit Pete Steckler / Nature Conservancy

It was perched too high above the stream for the baby eels to swim through. Zankel says it was an obvious opportunity for the nonprofit to step in. 

“So our staff contacted the town and said, 'What do you think about this?'” he says. “And the town said, 'We’d love to talk to you more about that.'”

Together, they asked the state to help fund a new culvert with a new grant program for coastal resilience.

In the process, the Nature Conservancy worked with the state to assess all of New Hampshire's thousands of other culverts for their climate vulnerability.

What they found, Zankel says was that “probably fewer than a dozen were designed and put in thinking about the kinds of rain events and storm surges that are going to come with climate change.”  

Further reading: Resilient Tidal Crossings, N.H. Department of Environmental Services, 2019

So the Newmarket project became a model. It shows it is possible to make old infrastructure ready for climate change. It also shows how complicated that will be.  

Up-front investment

Nature Conservancy project manager Pete Steckler leads the tour group down to the edge of a wide, muddy pit that now interrupts the flood-prone road in Newmarket. The old culvert used to run through this space. It was about 3 feet wide.

Lubberland Creek in Newmarket will now travel under Bay Road through a 16-foot-wide box culvert set to be installed in this pit.
Credit Annie Ropeik / NHPR

“You compare that pipe to this hole in the ground, which will fit the new structure, and I think you can get a sense of the magnitude of the upsizing or upgrading of this road-stream crossing,” Steckler says.

This tour was in early September, and the new culvert was due to be installed here by October.

The replacement is really more of a bridge – a 16-foot square opening beneath the road, with sloped rocky sides. Based on moderate sea level rise predictions, it should keep the road dry, let the salt marsh migrate inland and benefit eels and other wildlife.

It has taken seven years to get to this point. At least half a dozen state and federal agencies were involved, plus the town, Nature Conservancy, UNH and private contractors.

Together, they spent $400,000 on studies, engineering, permits, road closures and construction.

"Four hundred thousand-dollar projects are tough to come by,” says Steve Couture, who leads the coastal program at the state Department of Environmental Services.

He says spending that money up front will prevent costly damages in the long run. But the state and towns will need help to do it. 

“To become more resilient, it costs more than just replacing in kind, so somehow you have to make up that gap,” he says. “For New Hampshire, for projects like this, there’s limited in-state resources that can help, so a lot of it’s coming through the federal government.”

First of many

Congressman Chris Pappas, the Democrat who represents the Seacoast in Washington, agrees that federal funding is the missing link to make these resilience projects more do-able. He was at the recent culvert tour, and says thinks local examples like Newmarket’s will be key to securing more of that money. 

Congressman Chris Pappas speaks about the culvert project at the Nature Conservancy's Great Bay office.
Credit Annie Ropeik / NHPR

“For some of my colleagues who don’t believe climate science, they should open their eyes,” Pappas says. “I think if we can bring forward stories about how our districts are being affected by severe storms and sea level rise … perhaps that’ll help.”

For town officials in Newmarket, the long-awaited upgrade of their most problematic culvert has been an inspiration.

Next, they’re seeking funding for resilience upgrades on a downtown park. It sits on the Lamprey River and is prone to costly floods. 

Further reading: Changing Flood Risk in the Lamprey River Watershed, UNH, 2018

Town council chair Toni Weinstein says to get more taxpayer buy-in on projects like that, they'll need to sell people on the broader benefits - like protecting the neighboring mill buildings the town recently redeveloped.

“I don't think that anybody wants to lose that,” she says. “So as long as we educate the public for why we’re doing projects, then they’ll come along.” 

The more awareness they can spread, she says, the faster the town will be able to adapt. 

This post has been updated to correct the spelling of Steve Couture's last name.