The Maine Department of Transportation expects to issue initial engineering plans to replace the 90-year-old Deer Isle Causeway in late February or March, moving replacement of the 4,100-foot stretch of roadway across Eggemoggin Reach another short step closer to reality. But construction—currently planned to commence in 2026—can’t start soon enough for year-round and seasonal residents of Deer Isle.
While islanders had grown used to an occasional overtopping from king tides coinciding with Nor’easters over the past 20 years, concerns about the thin strip of pavement escalated dramatically after 2024’s January storms, when a foot-and-a-half of water covered the causeway.
The state was forced to temporarily close Route 15, the only connection between the island towns of Stonington and Deer Isle, and the Blue Hill Peninsula. For a short period of time that felt intolerably long to residents, ambulances weren’t able to transport patients to Blue Hill Hospital, fire trucks couldn’t reach Little Deer Isle in case of a fire and Versant Power crews couldn’t cross onto the island to remove and repair downed lines.
“It was not just a few inches,” recalled Deer Isle Town Manager Jim Fisher. “It was 18 inches underwater, and rocks were thrown up on it. So even people who tried to venture across it were hitting rocks, and it just was a terrible situation.”
For a short time, ambulances weren’t able to transport patients to Blue Hill Hospital, fire trucks couldn’t reach Little Deer Isle, and Versant Power crews couldn’t repair downed lines.
Adding insult to injury, when the tidal surges from each of the storms receded, they pulled away tons of stones and soil, undermining the integrity of the exposed road surface. In the days and weeks that followed, contractors hired by DOT feverishly rebuilt portions of the causeway abutments that had washed out.
“It had been identified as a top priority for years,” said Fisher. “And after last year’s January storms, the Maine Emergency Management Agency ranked it among its top two or three priorities. But it has always been vital for the 3,000 year-round people who live down here, and it’s also important for commerce—the biggest lobster landings in the state are in Stonington—and it’s important for tourism, because our population probably doubles in the summer.”
Linda Nelson, Stonington’s Economic and Community Development Director and co-chair of the state’s Infrastructure Rebuilding and Resilience Commission, said the causeway’s viability impacts people off-island as well.
“Ours is the largest port in the state,” she said, “so it’s a vital part of Maine’s economy. It’s the southern terminus of State Route 15, a vital transportation corridor that starts at our port and goes all the way up to Canada, connecting to all parts of the state. And we’re the second largest island in the state. I think we have to remember these things and keep them out in front of everybody.”
HISTORY
Prior to the construction of the causeway and adjoining Deer Isle Sedgwick Bridge, goods and people reached the island via steamboats from Rockland or a 130-year-old family-run ferry service between Sargentville and Little Deer Isle.
But the growing affordability and popularity of automobiles put pressure on state and federal officials to connect the island to the mainland with a real roadway. In 1927, state representative George E. Snowman of Little Deer Isle introduced a bill to fund causeway construction between Deer Isle and Little Deer Isle, and won a $15,000 appropriation to begin work. It was a vital factor in attracting federal and state assistance to build the bridge that crosses the Reach from Little Deer to the mainland town of Sedgwick.
The Hancock County Emergency Management Agency simulated a truck accident on the bridge—it carries an average of 4,130 vehicles per day, including 18-wheelers and small trucks…
The original causeway opened in 1938. It followed a natural sand bar that was submerged at high tide and was known locally as Scott’s Bar. The narrow roadway follows the serpentine path of Scott’s Bar from one end to the other, an unfortunate route that has resulted in regular accidents over the years. Its construction also ended the exchange of water in the local basin between Penobscot Bay and the Reach, which local shellfish harvesters argue has harmed its ecological diversity.
FIVE ALTERNATIVES
While the causeway had been a local concern for at least two decades, state transportation officials launched the replacement project with scoping meetings in 2023. In addition to input from both towns and the Hancock County Emergency Management Agency, the state solicited input on environmental impacts from both the University of Maine and the Maine Center for Coastal Fisheries. The MCCF also helped with the long and arduous process of gathering public input over the next year.
“Designing a new piece of public infrastructure is a drawn-out process because you need a lot of community input,” Nelson observed, listing a series of presentations at select board meetings, town halls, and “virtual watch parties” that took place on Zoom. “But now we are in serious, let’s-build-this-puppy, engineering mode.”
In August of 2024, preliminary designs from StanTec Engineering produced five alternatives. All of the designs would raise the causeway from nine feet to about 13 feet—about 2 feet above the direst predictions for sea level in 2100—and widen the road to 32 feet, adding five-foot shoulders on either side. The designs would also include slope stabilization to prevent further erosion.
“It was sort of three alignment options, and then two possible culvert or bridge options,” Fisher said, summing up the alternatives. One alignment followed the current path of the causeway, while the other two involved realignments that would push the roadway further out into the water between Deer Isle and Little Deer.
“Each further alignment added $5 million or more to the ticket,” Fisher said. “So, they went with keeping the current alignment.”
Already eyeing a $20 million price tag for the most basic design, the state decided against including culverts or a bridge to the plan.
“Our option will result in more resilient and dependable causeways using conditions observed during recent storms and 2100 sea level projections from Maine’s Climate Plan,” DOT Commissioner Bruce Van Note wrote in a letter to town officials explaining the process. “Indications from the UMaine study team are that there will be a finding of minimal ecologic benefit of a bridge or minor span openings through the causeway systems.
Accordingly, we are proceeding with a design that does not include such openings.”
MIXED RECEPTION
Reception from islanders was decidedly mixed. In written comments on the project collected in 2024 after the five alternatives had been presented, many residents worried that the state was under-engineering the replacement. “It appears that your ‘experts’ in Augusta have used ‘tidal data’ as the determining factor in setting the new height of the causeway,” one objected. “It is NOT TIDES that are causing and will continue to cause flooding. It is WEATHER.”
Others were disappointed about the lack of an opening between the Reach and Penobscot Bay.
“The [UMaine] study focused on potential short-term impact on commercial fisheries but did not address the current impact of that separation and any long-term impact on the adjacent sea beds, habitats and their biology,” another resident wrote. “We will likely have only one opportunity in our lifetimes to open flows between the two bodies, and it should not be missed at this time.”
Acknowledging such objections, Van Note cautioned that deviating from the preferred design would not only raise the price tag but possibly endanger the project’s completion timeline.
“Continued efforts by advocates to seek additional study and more complicated design concepts could slow environmental processes and delay the project delivery schedule,” he warned in his letter to town leaders.
“It is difficult, of course, to know how fast sea level rise will be,” Fisher conceded. “There are some concerns that we’ve underestimated the speed at which sea level will go up… But if the tide was 18 inches deep during that storm and they’re going up 51 inches, that’s pretty good. And I’ve learned that if you ask enough times, the answer becomes no.”
NEXT UP: THE BRIDGE
The causeway, of course, is just half of the island’s transportation equation.
Nelson and Fisher are already lobbying Van Note to consider replacing the Deer Isle-Sedgwick bridge, which requires expensive annual maintenance and inspections. When the Hancock County Emergency Management Agency simulated a truck accident on the bridge—it carries an average of 4,130 vehicles per day, including 18-wheelers and small trucks—it projected a catastrophic structural failure that would, in real life, mark the end of the span’s useful life.
“We’re trying to find a process or path forward for replacing the bridge, and that’s a bigger, much bigger undertaking,” Fisher said. “I don’t want to give the impression it’s dangerous, but it’s obsolete and it needs to be replaced. The DOT considers that a billion-dollar job. So, it’s an enormous expense.”
And one that the state and federal government are unlikely to take on in the near-term.
“This bridge has been and remains a major focus and priority of MaineDOT … because of the very significant costs and challenges associated with replacing the structure,” Van Note wrote. But based on recent evaluations, the department “concluded that the critical components of the bridge (the towers, main cables, piers, abutments, and anchorages) can remain in service at least another 20-25 years.”
