HARPSWELL — With the longest coastline of any town in Maine, Harpswell is defined by the sea.
And the sea is rising.
Tides measured in Portland Harbor have risen 7.5 inches in the last century, according to data from the Maine Geological Survey. As ice caps and glaciers continue to melt and the oceans warm, scientists believe sea levels will only rise higher.
That means higher tides and bigger storm surges will increasingly have an impact on infrastructure built for a different time. In a town like Harpswell, where 20 percent of residents live within 250 feet of the coast, some town officials believe planning has to start now.
“A king tide this year … topped some roads over already,” Mary Ann Nahf, who serves on the town’s Conservation Commission, said at a workshop Tuesday, June 21. “This is important enough to start talking (about) now.”
The Conservation Commission is leading a series of workshops this summer aimed at educating private road owners about how to plan for sea level rise. More than half of the roads in Harpswell are privately owned, according to Nahf, giving private road owners and associations an out-sized role in the planning process.
The commission sent about 300 letters to homeowners on private roads in Harpswell asking them to attend the first workshop. About 35 people showed up.
The conservation commission’s next workshop is on how to form official road associations, which can help in leveraging grant money for road work. It will be held 6 p.m. Aug. 24 at the town office.
Otey Smith, of Tondreau Point Road, said he and his neighbors are already thinking about the need to replace culverts on their road. One is currently about 3 feet above high tide, he said.
Residents like Smith can see parts of town that will be impacted in different sea level rise scenarios: The town has maps on its website created by the Maine Geological Survey showing what areas would go underwater if the sea levels rise 1, 2, 3 and 6 feet, respectively
Paul Ciesielski, a marine geologist who serves on the Conservation Commission, said according to estimates from the Proceedings of the Natural Academy of Sciences, Harpswell could experience a 2-foot rise in sea levels as early as 2050. That would put 12 public roads at risk.
Matt Craig, a program coordinator at the Casco Bay Estuary Partnership, spoke to workshop attendees about the importance of good culverts for marsh migration.
As seas rise, saltwater marshes will be pushed inland. This is a natural process, he said, and maintaining marshes is critical; they provide important habitat for wildlife and commercial fisheries, and buffer storm surges.
He urged the private road owners to consult with experts and engineers when replacing culverts in tidal environments. Replacing a bad passage with a larger culvert or bridge could improve a wetland, and keep roads intact in the long run. He said grants were available for such work.
Representatives from the Cumberland County Soil and Water Conservation District also spoke, stressing that culverts improperly designed for flow not only wreak havoc on ecosystems, but can result in blown-out roads – a high risk in extreme weather events when emergency passage may be critical.
“We’re not going to hold (sea level rise) back,” said Troy Barry, a district engineer. “Don’t fight it, but adapt.”
Dave Duering, of Wallace Shore Road, said he was thinking about risk when he and his road association recently replaced culverts with structures that didn’t restrict the flow of the marsh.
In a weather emergency, “what if it’s my house the fire department or police are trying to get to,” and a road is blown out, he said. “What’s that worth to you?”
The presenters said the Casco Bay Estuary Partnership and County Soil and Water Conservation District would be available for site visits and consultations for road owners looking to improve their infrastructure.
After the meeting, Smith, the Tondreau Point Road resident, paused to consider the impact the new information would have on decision-making for his private road.
“It just kind of reinforces what I was already thinking,” he said.
A parking lot and dock on Wallace Shore Road in Harpswell that flooded during a king tide Feb. 9.
This section of Long Point Road in Harpswell, which crosses a marsh, already floods at some tides and is susceptible to just a 1-foot rise in sea levels.