A truck heads off Deer Isle along the island's recently repaved causeway in August 2022. The Maine Department of Transportation has started an evaluation of the causeway, which locals are increasingly worried will fall prey to rising seal levels. Credit: Ethan Genter / BDN

Earlier this year, chunks of the causeway that provides the only way onto Deer Isle were wearing away. In a few places, the crumbling edges of asphalt had encroached so far that they passed the road’s white fog lines and into the roadway itself.

Though local officials have long been worried about the effects of rising sea levels on its coastal infrastructure, the cracks served as a reminder that the causeway is a vulnerable pinch point that could throw Maine’s busiest lobster port into chaos with rising sea levels.

But new efforts are underway to figure out how to make the causeway more resilient.

The state recently started evaluating the impacts of coastal flooding on the less-than-a-mile stretch of road between Deer Isle and Little Deer Isle and is developing a range of possible solutions for the causeway. Local town leaders and public safety officials are also having a planning exercise next month to prepare themselves should the causeway ever be blocked or wash away.

“This is the first time we’ve really looked at it from a holistic standpoint,” said Dale Doughty, the director at the Maine Department of Transportation’s planning bureau.

By road, the causeway is the only way to get to Deer Isle, an island that encompasses both the towns of Deer Isle and Stonington. Landbound travelers must first cross a two-lane cable bridge that arches over Eggemoggin Reach and connects Sedgwick and Little Deer Isle, another island that is part of the town of Deer Isle.

The causeway, which connects to the eastern end of Little Deer Isle, had its crumbling patches repaved earlier this summer during regularly scheduled DOT maintenance.

Built in the late 1920s, the causeway sits atop of a sandbar. At low tide, beaches and mudflats are exposed on either side of the road. At high tide the water level seems almost as high as the pavement.

Officials worry that with rising sea levels, the causeway will be in more danger, potentially putting Deer Isle and Stonington literally out to sea. Right now, rocks and seaweed can wash up on the road in bad storms.  

Kathleen Billings, the Stonington town manager, said last year’s road washout in Gouldsboro made her worry about the causeway. She said the same of the Jackman washout this summer, where drivers had to take a 143-mile detour — but noted that such a solution wouldn’t work for the island.

“There’s no detour for us,” Billings said. “It would bring everything here to a standstill.”

The issue of sea level rise isn’t new for the island, but it’s become an increasing concern. Some see changes to the road as the only thing to do.

“We have these two points of vulnerability: the causeway and the bridge,” said James Fisher, the Deer Isle town manager. “I think we need to raise and widen the causeway to make it more climate resilient.”

DOT plans to look at the causeway’s current conditions and explore the effectiveness of different paths forward, according to Doughty.

They could include anything from the status quo, to better protections from the ocean for the existing roadway, to raising it. A preliminary report on potential alternatives and their effectiveness for the road is expected next spring. Once it’s complete, DOT will start to consider what options might be feasible.

In addition to the local emergency preparedness meeting, town officials will also hold a public meeting next month to report out what they’ve learned and listen to how people would be affected by a potential closure.

For Linda Nelson, Stonington’s economic development director, it’s also a way to signal to transportation planners that the causeway needs to be a priority.

In 2021, Stonington, which holds the title of the most valuable lobster port in Maine, caught $73.2 million of the crustaceans. The fishing industry is the economic driver of the community and Nelson worries what would happen if lobsters, almost all of which are destined for plates off-island, couldn’t pass over the causeway.

“We are trucking thousands of pounds of lobster across that causeway every day, not to mention the employees that come over to catch them,” she said. “It needs to rise to the top of the to-do lists.”