At Tenean Beach, city, state pull from nature’s toolbox to address coastal flood paths

As a low-lying coastal city, Boston is at heightened risk for coastal flooding. To examine the challenges and opportunities of coastal resilience efforts, the Banner is digging into three sites along the metro-Boston shoreline where flooding could pose high risks and where solutions are being crafted to create new models for the future. Part 1 of the series examines Tenean Beach in Dorchester.

Tenean Beach was dry when Maria Lyons stood on it Feb. 15, but it often isn’t that way. Days before, the king tide had swallowed up the sand, the play structures, the athletic courts and the parking lot. Trash and plant debris still littered the ground.

Maria Lyons, a retired science teacher, stands on Tenean Beach in Dorchester, Feb. 15. The beach, which sits at the mouth of the Neponset River, is a high-priority site for coastal resilience efforts from the city and state.

White hair whipping in the sea breeze, Lyons, a retired elementary school science teacher, recalled a couple of storms in 2018 where the flooding went as high as the embankment that supports the Southeast Expressway, blocking one entrance and exit into the Port Norfolk neighborhood where she lives.

“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.

Tenean Beach in Dorchester. PHOTO: COURTESY OF URBNPARKS

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.”