A Maine Department of Transportation plow truck clears storm-propelled debris from the Deer Isle causeway in 2007. Credit: Rich Hewitt / BDN

After years of hearing concerns about the damage caused by climate change, the state has decided to rebuild the Deer Isle causeway.

The low-lying causeway connects the islands of Deer Isle to Little Deer Isle, which is connected to the mainland by a cable-suspension bridge. For most residents of the town of Deer Isle, and for all Stonington residents, the Route 15 causeway is the only way to get to and from the mainland other than by boat.

Officials with the Maine Department of Transportation said they are just beginning the study phase of the project, which will consider various alternatives. Because the causeway winds for nearly a mile across the mudflats between Little Deer Isle and Deer Isle, and because island residents still will have to be able to drive on and off island while the project is underway, the full project is likely to last several years.

“This is a very complicated project,” said Martin Rooney, a planner with the agency. “There are plenty of causeways in the state of Maine, but there aren’t any like the Deer Isle causeway that I’ve been on. There’s no detour route.”

For several years, local officials in the towns of Deer Isle and Stonington have been raising concerns about the vulnerability of the causeway, which was built in the 1930s. At times, storms and unusually high tides have washed debris onto the narrow road, blocking passage and requiring highway workers to clear it of stones and seaweed. It has flooded over at times when storms and high tides have coincided, which is causing erosion.

State officials held a public meeting Tuesday with local residents at Deer Isle-Stonington Elementary School and plan to hold two more during the study phase of the project, which is expected to last a year.

The state will consider raising the causeway as much as 4 to 6 feet, and whether a portion of the new causeway should include a bridge so water can flow more easily between the two islands to and from Eggemoggin Reach. The state also will consider making the causeway wider to accommodate large trucks and for possible bicycle lanes.

The project also is expected to include a low-lying portion of Route 15 at the immediate southern end of the suspension bridge over Eggemoggin Reach. That section of road also is susceptible to storm flooding and sea level rise, MDOT officials said.

MDOT and local officials said they recognize the urgency of the project, given the deterioration of the road, but said they have to be deliberate and follow certain planning procedures — including a mandated “do nothing” option — in order to qualify for federal funding. They said they expect the federal government to fund 80 percent of the undetermined project cost and for the state to foot the rest.

After the study phase is completed, likely at the end of next summer, the design phase could take another 12 to 18 months and then construction could take an additional 18 to 24 months beyond that. The entire process could mean the new causeway isn’t completed until 2028, even if everything goes smoothly, officials said.

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....