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What do culverts have to do with climate change?

Federal investments in New Hampshire are meant to help the state become more resilient in the face of rising sea levels. But a lot of work remains

Steve Couture (left) met with Thomas Ballestero, and Matt Thorne of the Nature Conservancy to discuss efforts to update a culvert that can help protect salt marshes as sea levels rise. Photo: Amanda Gokee, Globe staffAmanda Gokee, Globe staff

An unassuming culvert along New Hampshire’s Route 1A near Rye Harbor could play a key role in protecting one stretch of salt marsh from climate change. That’s because it’s sandwiched between the ocean on one side and the Awcomin Salt Marsh on the other.

Salt marshes are connected to the tides, so as sea levels rise, they need somewhere to go or they’ll disappear, taking an important ecosystem with them.

“Salt marshes live between mean tide and mean high, high tide, and as sea level rises, it’ll drown that out unless it can migrate landward,” said Thomas Ballestero, an engineer and professor of hydrology and water resources engineering at the University of New Hampshire.


“So if you have a site where it can’t migrate because there’s infrastructure, we’ve lost it forever,” he said. “In a site like this, this one has the possibility (of migrating because) there’s undeveloped land to the west.”

The culvert was in need of an expensive upgrade to allow that to happen. Ballestero said about 95 percent of salt marshes on the east coast are expected to disappear by the end of the century because of sea level rise.

That’s part of what’s driven state and federal interest in making three Seacoast culverts resilient to climate change. The project has received $2.9 million in federal funding focused on making improvements that can accommodate rising sea levels and increased precipitation.

But the need for coastal resiliency is much greater than just three culverts, according to state officials from the Department of Transportation, the Department of Environmental Services, and The Nature Conservancy of NH staff who gathered at the roadside culvert Tuesday, discussing the site with Richard W. Spinrad, administrator with the National Oceanic and Atmospheric Administration.

Spinrad’s visit highlighted investments in New Hampshire to promote climate resiliency through the Bipartisan Infrastructure Bill. He also used the visit to announce a new $20 million joint ocean mapping initiative with University of New Hampshire officials.


Twenty other culverts in the Seacoast are considered a high priority to be replaced, according to Steve Couture, who runs the coastal program through the Department of Environmental Services. He estimated the work would cost between $20 million and $25 million.

On top of that, “There are 11 crossings that currently flood, and 22 additional that flood at 1.7 feet of sea level rise,” he told the crew gathered at the culvert. He said 62 crossings provide about 5 acres where salt marshes could potentially migrate.

Spinard said building climate resilience should promote both economic development and environmental stewardship.

“I actually believe if we do this right we can see economic growth, we can see people more prosperous, we can see communities that are safer,” he said.

Spinrad also announced another New Hampshire initiative he said would help the state work toward that vision: a joint $20 million venture with the University of New Hampshire to construct a new ocean mapping facility.

The university will receive the first $10 million installment from NOAA in 2023.

University leadership expects construction on the new facility to begin within a year. Senior Vice Provost Marian McCord said she’s received requests from companies looking to co-locate for about a million square feet of space.

“It’s in our best interest to have students, faculty, our research scientists, and industry partners, and our government partners in a space where they can rub elbows,” she said.


The new facility will also include retail, dining, and “hundreds” of housing units for graduate students and industry professionals, although an exact number is not yet available, according to McCord. She said the project could create up to 1,000 new jobs.

New maps are needed for shipping, navigation, siting offshore energy, and forecasting, according to Spinrad.

Spinrad said current maps only cover about 50 percent of the coast, according to some estimates. The bottom of the ocean changes over time, so other existing maps need to be updated, he said.

“The need to update those maps and do the data acquisition is critical,” he said. Flooding in coastal communities is tied to precipitation, but is also impacted by how the ocean bottom is shifting over time.

Major shipping ports also need accurate maps for navigation, and the National Weather Service needs the information in order to make weather forecasts.

The new facility is important to what Spinrad called the “blue economy,” touching on commerce, transportation, clean energy, and gathering data to respond to climate change.

The university has already been working with NOAA on mapping for 24 years. The money for the new joint venture was available because of a $3 billion appropriation to NOAA through the Bipartisan Infrastructure Law, according to Spinrad.

Amanda Gokee can be reached at Follow her @amanda_gokee.