Solutions for a shifting coastline: Resilience solutions on the Metro-Boston shore

“One of them, I was at school working. And I couldn’t get into the neighborhood because [Conley] Street was all flooded, Morrissey [Boulevard] was flooded and the Neponset Circle was flooded,” Lyons said. “So there was no way in or out.”

She had to wait out the flooding at Dunkin’ before she could return home that night.

At the mouth of the Neponset River, Tenean Beach sits at one end of the Neponset River Greenway, which runs from Hyde Park through Mattapan to Dorchester. During summer months, the beach is an active recreation spot, with two athletic courts, a new playground built in 2022 and harbor views out toward the Rainbow Swash natural gas tank and Columbia Point. Even during mid-February, with temperatures hovering around 35 degrees, at least 10 cars sat in the parking lot.

It also is an early point of concern as the city of Boston assesses flood risk and coastal resilience. Coastal flooding projections, like the Massachusetts Coastal Flood Risk Model, suggest that the Conley Street underpass, which cuts under the Southeast Expressway, could become a significant flood pathway into nearby neighborhoods as soon as 2030. That kind of flooding could also impact the MBTA Red Line, which runs just behind the site.

In the city’s Climate Ready Dorchester plan, released in 2020, plans to address coastal resilience at the beach were designated a “near-term catalytic project” — functionally meaning it’s a high priority for the city to address, to keep flooding from entering more inland neighborhoods.

Much of the area around the beach is old industrial land, with plenty of pavement and hardscape. Efforts to make Tenean Beach more resilient, released in a June 2023 report, will move it in the opposite direction, opting instead for nature-based solutions.

Conley Street, which runs along one side of the park before crossing under Interstate 93, would be raised up to about 14 feet to create an elevated barrier to protect against flooding. The parking lot would be condensed, and the dunes would be expanded and supported with dune grass to limit erosion.

The project would also work to restore and care for Pine Neck Creek, part of the Neponset River watershed, which runs along the beach. The creek, which historically hosted diverse salt marsh vegetation, has been long impacted by invasive species and pollutants from upstream and roadway runoff. Healthy marsh vegetation can serve as an important buffer to help coastal regions recover from storms and adjust to sea level rise.

Those solutions can also be cheaper and more effective, said Mariama White-Hammond, the city’s chief of energy, environment and open space.

“In many instances, nature has been facing these challenges for a long time, and she’s been doing a better job than us,” White-Hammond said.

And they can come with a host of other benefits. Joe Christo, managing director at the Stone Living Lab, which works on nature-based coastal resilience solutions, said work like this can increase biodiversity, better manage stormwater and sequester more atmospheric carbon.

Chris Mancini is executive director of Save the Harbor/Save the Bay, a nonprofit that works to protect and restore the marine habitat along the shoreline. He said the work at Tenean Beach could serve as a model for work that should be done throughout the rest of the state, both for its nature-based solutions and for the cooperation the site requires between the city and a host of state agencies like the Department of Conservation and Recreation, which owns the land, the Department of Transportation, which is responsible for I-93, and the MBTA.

“You’re taking existing green space and creating more green space and nature-based solutions that can absorb storm surge, absorb flooding,” Mancini said. “And you have a really beautiful partnership between the city and the state, and in the future, even private entities, private developers. We’re going to really rely on those relationships to do this more commonly along the coast.”

The Tenean Beach proposal might also help people feel more invested in the solutions.

“I think you work to protect what you love; you fight for what you love,” White-Hammond said. “People are just less likely to fight for a building and an underground pipe than they are beautiful park.”

Lagging timelines hamper efforts

Though the Tenean Beach resilience efforts are a high priority, such projects can move slowly. As February wraps up, the Massachusetts Emergency Management Agency is submitting the project to the Federal Emergency Management Agency for funding through FEMA’s Building Resilient Infrastructure and Communities program, which funnels dollars to proactive resiliency efforts rather than responsive disaster spending.

That approval process can take as little as a year and as long as five years, said Delaney Morris, senior climate and coastal resilience infrastructure delivery project manager for the Boston Planning and Development Agency. Once FEMA awards the funds, Morris said the BPDA expects the project to take about three years to complete, pushing up to or beyond 2030, the first benchmark for flood risk projections.

Morris said the city’s priority is to address near-term flood pathways and that it is actively monitoring the situation along the coast and is ready to have the necessary conversations to make sure the efforts progress. The project will be useful, she said, even if it takes a while to get approved.

The Tenean Beach proposal aims higher than the 2030 benchmark, said Linh Pham, a senior associate at SCAPE Landscape Architects who worked as the project manager for the Tenean Beach work. Near-term flooding projections would require about 12 feet of elevation. Pham and her team at SCAPE aimed for 14 feet instead, the low end of longer-term projections.

That height was set, in part, based on limits of how much fill can be used in the space due to its proximity to the Neponset River Estuary, which is one of only 30 so-called Areas of Critical Environmental Concern across the state and the only one immediately in the Boston area.

White-Hammond said 2030 is a benchmark based on probability, not a strict deadline, but the city is working to address resilience as quickly as possible.

Boston has a head start on that work. White-Hammond cited the Climate Ready Boston plan first released in 2016, which mapped out areas of concern and what real solutions might look like, as “ahead of the curve,” compared to other low-lying coastal cities, but said it’s not possible to close the flood paths of concern — an effort which she estimated to cost in the billions — with municipal resources only. The cost estimate for the work at Tenean Beach specifically was projected to fall around $12 million.

Having to fall back onto federal funding to support resilience efforts has slowed the process.

“The process [of getting grants from FEMA] is not the most effective and efficient if I’m honest,” White-Hammond said. “Sometimes that’s been making projects be more delayed than we would like.”

Impacts, benefits could be widespread

For residents like Lyons, who live within walking distance of the beach and have an extensive archive of photo and video evidence of the flooding, the importance of coastal resilience infrastructure is obvious, but in a city like Boston, where about one-sixth of land is filled-in wetlands, stormwater and flooding impacts can be widespread.

“The Atlantic Ocean does not respect municipal boundaries or neighborhood boundaries,” said Christo, of the Stone Living Lab.

The flood paths the city is trying to close up can carry water a surprising distance into inland neighborhoods, White-Hammond said.

“If water is picked up along the coast, it will continue raging inland until it runs out of steam,” she said.

Beaches like Tenean are also important places for more equitable access to the city’s waterfront, as efforts like Resilient and Inclusive Waterfront from the New England Aquarium or the Waterways effort from The American City Coalition attempt to connect residents from more inland neighborhoods with the waterfront.

Tenean Beach has direct access by foot and by bike from communities in Dorchester, Mattapan, Milton and Hyde Park.

“If you live in Roxbury, if you live in Mattapan, you still have a beach … it’s just your neighborhood doesn’t abut it,” Mancini said. “There’s a place that’s yours and you’re going to go, and it’ll be lost if we don’t adapt and enhance those relationships.”■

But officials from both cities it touches are looking toward a future where the banks can be clean, the native salt marsh can be rejuvenated, the park can be more accessible, and the area can serve as flood protection for vital infrastructure and at-risk residential communities behind it as the area faces growing potential threats from a changing climate.

“Climate change is incredibly scary,” said Emily Granoff, who manages the project for Chelsea. “It’s going to have really terrible impacts for a huge number of people, especially in environmental justice communities, like Chelsea and Everett. We talk about that a lot at the federal level and at the state level, but small communities like Chelsea and Everett, we are taking action.”

The strip of land right around the Island End River Project offers little protection to the nearby New England Produce Center, the hub of fruit and vegetable distribution for all of New England and up into Canada. Further back, there’s transportation infrastructure like the Chelsea Commuter Rail station, one of Mass General Brigham’s outpost health centers, a high school, and the homes of about 5,000 residents.

All of that sits in a flood plain that could, under some projections, see up to four feet of flooding with storm surges by the year 2070.

To mitigate that flooding, the project, co-managed by both cities, will include construction of a storm wall, restoration of native marshland, renovations to a local park and the addition of a storm surge-control facility that will block one of the culverts that normally drain water into the river to keep water from flowing the wrong direction during storms.

“I can’t speak highly enough of how cool this project is,” said Patrick Johnston, who manages the project for Everett.

The resilience effort has received attention — and funds — thanks to U.S. Rep. Ayanna Pressley, who channeled $750,000 in federal funding to it through community project funding, formerly known as earmarks. That money was allocated in 2022 and officially delivered at a roundtable event in February of this year.

Pressley called the project “visionary” and said efforts like this are important for centering environmental justice communities. Only one census block each in Chelsea and Everett doesn’t qualify under the guidelines focused on income, language access and percentage of the population that is a minority.

“As policymakers advance the investments necessary to make our communities more climate resilient, environmental justice must be front and center,” Pressley said at the event. “It is policy and these budgetary investments that will make the difference in closing so many of the inequity gaps that we see persistent throughout this congressional district, but in particular in Chelsea and Everett.”

Building walls to keep out the water

One key piece of the Island End River Project will be a storm wall, running for just shy of 4,500 linear feet down Market Street on the Everett side of the project.

Compared to other pieces of the Island End resilience efforts, or some other coastal resilience projects in and around Boston, the example of “gray infrastructure” — projects using things like concrete or steel — is something of an outlier.

On the map of coastal resilience projects, where the city of Boston tracks the projects it’s planning or has done along the city’s 47-mile coastline, much is marked with the green of elevated parks and berms and the teal of nature-based solutions. The grey areas indicating seawalls and floodwalls appear in only a handful of spots, most of them industrial places like the cruiseport in Seaport or along the edge of the MBTA’s Orient Heights rail yard.

At Island End River, Johnston called the wall something of a second-choice solution. He said nature-based efforts would be preferable, but restrictions on the Everett side from its federal designation as a port area and a history of environmental contamination in the area limits what solutions the team can employ.

Partway down Everett’s riverbank, a confined disposal facility — a way of isolating contaminated substances — holds heaps of the river’s sediment dredged in 2007 and contaminated with byproducts from a coal tar production facility that existed alongside the river from the late 1800s until the mid-1900s.

“We have already pushed nature so far that there’s nothing for us to do but make another built solution,” Granoff said.

For people working in coastal resilience, nature-based solutions are often preferable, offering additional benefits like managing stormwater, increasing biodiversity, sequestering atmospheric carbon, or providing green space for community members.

They can also have a longer lifetime. The wall, once installed, will be designed to withstand strong waves from the river side, and the possibility of truck or car drivers colliding with it from the Market Street side, Granoff said. Even with the best efforts, however, it will eventually need to be replaced or repaired in a way nature-based solutions, when done right, won’t require.

“Nature-based solutions are, when you can do them really well, self-healing,” Granoff said. “They’re more aesthetically attractive; it often results in creating open space that we can enjoy, whereas this is a wall, when you get down to it.

Supporting nature’s ‘big sponge and filter’

The use of the storm wall will not replace nature-based solutions at the site altogether. On the other bank of the river, existing salt marsh will be revitalized with work on removing trash and invasive species like phragmites, a type of tall reed brought over by Europeans that has since spread wildly across the United States, often outcompeting native species.

Salt marshes used to be plentiful along the New England coastline, but climate change and development decimated the habitat. According to a 2005 paper that looked at historical maps to calculate an estimate for how much marsh had been lost over the years, by the early 2000s, Massachusetts had lost 41% of the salt marsh it had in 1777. The Boston area specifically had lost about 81%.

“That kind of saltwater marsh used to be a huge part of this area,” Granoff said. “It will do a lot to help, like, absorb and retain water.”

The marshes, like the one the Island End River project will restore, provide a host of benefits, slowing and buffering water coming in from tides and storm surges and filtering nutrients and contaminants in runoff coming toward the harbor.

Robert Vincent, an environmental scientist and the assistant director for advisory services at the MIT Sea Grant College program, called the marshes “a big sponge and filter.”

They can stabilize coastlines, collecting sediment and plant material through a process called accretion to grow and create a natural, raised area that can protect against tides and floods. They also provide habitat for both land and sea creatures, like birds, crabs and fish.

And healthy marshes are major “carbon sinks” — areas that collect and hold more atmospheric carbon than they release. According to a 2023 report from the Environmental Protection Agency that Vincent helped author, they can hold between four and 10 times more carbon than the same size area of a forest — carbon that is stored by the marsh, rather than contributing to climate change.

But rising seas pose challenges to the health of salt marshes. Increased flooding on the marsh surface can prevent plants from growing, which eliminates the protective nature of the marshes, and releases the carbon they’ve stored back into the atmosphere.

Development, especially between the mid-1800s and the 1970s, when the federal government and general public found greater recognition of the benefits of the habitat, also reduced the size of marshes across the region.

Vincent said he’s excited to see increased efforts around salt marsh restoration, and said he thought more coastal resilience efforts should include the marshes as an element.

“We’ve lost so much of this habitat, and it’s very important to continue to restore and conserve these habitats,” he said.

Resilience across city lines

Just past the current reaches of Island End River, the border between Chelsea and Everett takes a strange bulbous bend through the New England Produce center, the kind of line Granoff said no surveyor would do without good reason.

The shape is a memory of the original path of the Island End River, which was about twice its current length, and which marked the boundary between the two cities before a little over half was filled in.

Though the project falls right on the municipal line between Chelsea and Everett, it isn’t falling between the cracks. The work has prompted an intermunicipal agreement — a deal between the two cities passed by both city councils and signed by both executives that sets rules for the project managers to work together — and cost-sharing agreements that will impact both the project’s construction and maintenance.

The state, too, recognizes that resilience efforts need to cross official boundaries. As part of Resilient Coasts, an initiative announced by the Healey-Driscoll Administration in November, the state’s Office of Coastal Zone Management will create a system of coastal resilience districts along Massachusetts’ about 1,500 miles of shoreline.

Those districts will take into consideration things like physical characteristics of an area and vulnerabilities that might benefit from a shared resilience strategy but will ignore jurisdictional distinctions.

“One of the really key priorities here within Resilient Coasts is to bring this planning process and even the visioning of what resilience means to Massachusetts, beyond the municipal level, knowing that these climate impacts are not going to follow municipal boundaries, or even state boundaries,” said Lisa Berry Engler, who at the time of a January interview was assistant secretary and director of the Office of Coastal Zone Management. She has since transitioned to serve as deputy managing director of offshore wind at the Massachusetts Clean Energy Center.

The intermunicipal agreement at the heart of the Island End River project isn’t common, said Granoff — in her whole career with state and local government she hadn’t heard of that kind of partnership until her work on this project — but it doesn’t mean municipalities aren’t coming together in other ways, said Julie Wormser, senior policy analyst at the Mystic River Watershed Association.

Across that watershed, 20 cities and towns have joined the Resilient Mystic Collaborative, a coalition of municipalities working together to address flooding and resilience as it relates to the river. Island End River is a tributary of that larger body.

Together, they’re working on nine interventions — including the work at Island End River — along the Mystic and Charles Rivers that would close flood pathways and prevent flooding in about 7,500 acres of land across 15 surrounding municipalities.

“Climate change is really a collective action problem,” Wormser said “You do have to manage climate at a regional level and here’s an example.”

All of those projects have to happen in conjunction and in coordination.

For example, just building the wall and restoring the marsh at Island End River will prevent the worst of the predicted four feet of flooding that would come from that direction, but without raising the Amelia Earhart Dam and Draw Seven Park in Somerville further up the Mystic River — or without raising it enough — water could still seep around and leave at least a few feet of flooding in the area.

“When we’re talking about floodwater, we need to all be pulling in the same direction,” Granoff said. “There’s no way it’s possible to just protect ourselves, nor would we really want to.”■