STORMS ACROSS Massachusetts have been growing in strength, with deluges this year sending bacteria-laden stormwater into the ocean and wreaking havoc in flash floods. The state’s environmental agencies are gearing up for future storm surges and sea-level rise by proposing new regulations on development in at-risk coastal regions and updating the data sources used to estimate heavy rainfall for the first time in more than 60 years.
“We cannot continue a business-as-usual approach if we want to build more resilient communities,” said Massachusetts Department of Environmental Protection Commissioner Bonnie Heiple in a statement Friday announcing the proposed regulations. “With these regulations, we’ve integrated the latest science and green infrastructure techniques to mitigate climate change impacts and protect residents, municipalities, and businesses from costly rebuilding efforts.”
The proposed regulations impact structures and land inside the state’s coastal floodplain – home to nearly $55 billion in structures, including about $40 billion of residential buildings, across the state’s 78 coastal communities.
“That’s the area that floods during a big storm,” said Kathleen Baskin, assistant commissioner of the bureau of water resources at MassDEP. “We’re all familiar with where we might go down to the beach and see the waves coming in right at the coastline. That’s the area that we’re looking to protect.”
Within that plain, the regulations would broadly require new construction to mitigate potential flood risks, which may involve building elevated homes or restoring dunes and beaches or wetlands and salt marshes around the property to collect and drain water, among other environmental benefits.
“The idea is that we would be preserving the natural shoreline, so that wave energy and tidal changes are impacting the coast naturally instead of just barreling into the built environment and causing greater erosion,” Baskin said, “and we’ve certainly seen a lot of that over the last several years.”
The mitigation requirements would apply to new development and redevelopment, officials said.
If an existing property were updating its plumbing, for instance, the new system would need to comply with these new regulations. But there are carveouts – single-family homes and housing developments with four or fewer units are exempt from the stormwater requirements. New housing developments with five to nine units per lot must meet new standards only to the extent “practicable,” officials said.
Developers who choose to use more stormwater management solutions like trees and buffer zones instead of traditional infrastructure like piping will receive “Green Site Design credits” based on the amount of stormwater managed through those methods. The credits would not be financial offsets, but the state Conservation Commission would review projects and excuse traditional mitigation obligations depending on the amount of natural mitigation proposed.
“The development community is excited about this too, because it’s actually less costly to put in these natural solutions,” Baskin said.
These regulations are the first volley in wetlands and waterways updates, Heiple told reporters, with more proposals to come. Stakeholders will have until March 1, 2024, to submit comments on the proposed new regulations.
Exempting small units from the stormwater regulations is an effort to offer them flexibility and focus on the major drivers of stormwater damage, Heiple said. Larger building projects tend to have more impervious surfaces like pavements. “Those are the types of developments that really require this updated thinking on how to design the stormwater management system,” she said, “to deal with more of that water on site and less of it flowing out into the municipality.”
Predicting rainfall and flood risks is much more difficult when the state’s data predates the moon landing, climate officials noted. The new wetlands regulations include replacing currently used 1961 data with 2019 data from the National Oceanic and Atmospheric Administration.
Using the old data posed risks like underestimating the piping needed in stormwater systems – leading to the kind of overflow and flooding seen several times in the Bay State just this year. Storm effects aren’t limited to the coasts. Hundreds of acres of Western Massachusetts farms flooded. Tornados landed in Fitchburg.
“The urgency of these regulations is underscored by this week’s major rainstorm causing extreme flooding, power outages, damage to homes and businesses and most tragically, a death. How we manage water has profound implications on not only our environment, but also public health and safety,” said Emily Norton, executive director of the Charles River Watershed Association, in a statement. “We are pleased that these proposed regulations offer so many improvements in terms of updated precipitation models, stricter rules around building in floodplains, more consistency for developers and municipalities between state and federal rules, and more.”
The regulation changes would treat the residential parts of the coastal floodplain consistently with the way the state treats coastal resiliency around beaches and wetland resource areas, DEP officials said. With the updated flood maps and precipitation estimates, about 10 percent of the area most vulnerable to sea level rise in storm events but not covered by existing regulations, would be impacted by these new regulations.
New development would not be permitted in what is referred to as the “velocity zone,” where sea level rise and serious storm events can cause waves over three feet.
“In that outermost zone where wave action tends to be over three feet tall, there would be no new development permitted,” Heiple said. “So these houses that are being built in areas that are increasingly perilous to build, the proposal is that that type of development would no longer be allowed. Redevelopment would still be allowed subject to certain standards.”
Beyond that, “we’re allowing building and asking that they take precautions in how they build, but it’s not that we’re blocking out entire chunks of coastline,” she said. “It’s just as you go closer to the ocean, that’s where we’re drawing the line.”
