A seawall on a bluff in Bar Harbor. Long lawns with large trees are one of the worst ways to manage erosion on a bluff, said Peter Slovinsky, a marine geologist with the Maine Geological Survey, but it’s often difficult to dissuade homeowners who prefer the views and the aesthetic. Photo by Kate Cough.

ME - The sea is rising, and so is the angst for coastal homeowners

Before Walt Dunlap moved in 2011 to the shores of Maquoit Bay, just south of Brunswick, he did his homework. A licensed land surveyor, Dunlap knew the steep banks sloping down to the ocean were unstable and prone to erosion.

The house stood just 30 feet from the top of the bank, and Dunlap, who left South Carolina to escape a rising sea, “just wanted to make sure that we had something that was not going to disappear overnight.”

Dunlap surveyed the Freeport property himself, using 1947 maps as a baseline. The top of the bank hadn’t moved, and while he knew erosion at the bottom was possible, the lower bank was camouflaged by dense foliage and vegetation, making it difficult to see just how much the soils were crumbling. The Dunlaps signed the papers, came up seasonally for a few years, then moved full time in 2015.

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The more time they spent, the clearer it became: The bottom of the bank was slipping into the ocean. The shallow bay, exposed to the prevailing southwesterlies, was battered by increasingly intense winds and storms; waves gouged out the bank from below, while heavier and heavier rainfall pushed the soil down from above.

“We didn’t appreciate that there might be a problem.”

The cycle of shoreline erosion is a natural process that has been going on as long as there has been land and sea: Bluffs and dunes crumble, feeding their soils and nutrients into the mudflats and marshes below. The shoreline shifts landward, stabilizes for a while, then wears away again.

“Erosion leads to stability leads to erosion leads to stability — the overall trend is this feature moving landward in response to sea level rise,” said Peter Slovinsky, a marine geologist with the Maine Geological Survey who has advised communities on how to deal with an encroaching ocean for more than a decade.

The problem arises when humans build barriers to that movement: homes, walls, ice cream shacks, boardwalks, hotels. Solid, immovable structures, like the seawalls and bulwarks scattered along the state’s bluffs and beaches, make the problem worse — waves hitting the wall reflect down and up, scouring out sand and soil at the base, and around the edges. As a result, water in places with walls is much deeper, and “because the water’s deeper, you can get much larger waves there,” said Slovinsky.

Walls, which have to end somewhere, also accelerate erosion around their edges. “Because this is now eroding, the property over here says I need a wall, then the next one, then the next one, then the next one,” said Slovinsky. “So it’s kind of a perpetual problem.”

Figures are hard to come by, but those who work along the coast say they’re seeing more and more homeowners armoring their properties against erosion with everything from native plants and strategically placed rocks to large granite walls and bulwarks.

When the Dunlaps noticed in 2015 they were losing the bottom of their bank, they immediately set about remedying the problem. The couple hired a landscaping company with experience in shoreline stabilization; the company ripped out the invasive vegetation that had grown up along the bank, and replaced it with 100 native plants and an engineered, porous fabric to help keep the soils in place. The Dunlaps own about 50 feet of shoreline; the plantings and permitting cost roughly $12,000, said Dunlap — money the couple was willing to spend as long as it helped keep the sea in the bay and not their living room.

What the Dunlaps did — planting native plants — is precisely the kind of fix the Maine Department of Environmental Protection would like to see coastal property owners implement against erosion. The plantings were part of a “living shoreline,” a system designed to shore up the bank while allowing some soil to fall away, feeding the wetlands or flats below, while not exacerbating the problem in the way walls or bulwarks do.

Except, say engineers, living shorelines often don’t work — at least in Maine, with its strong winds and powerful tides.

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