The condo Casey Chaffin shared with her mother in Clinton is near the Wachusett Reservoir, but along a gentle slope where flooding has never been a problem. Importantly, the neighborhood is not on government maps of flood zones.
Yet when it started raining hard on March 15, 2010, the ground outside quickly became saturated, and it wasn’t long before water seeped into the basement, and then slowly rose until everything they had stored down there was underwater, including two lifetimes of memories in photo albums and heirlooms that were destroyed.
The record-shattering storms that dumped a foot and a half of rain on a swath of Massachusetts in March 2010 did more than just ruin the Chaffins’ personal effects. It also exposed how poorly prepared we are for a future when climate-fed deluges could be more frequent and more intense, as a new analysis of the 2010 flooding found that most of the homes that suffered water damage were outside expected flood zones.
“There is a lot of attention, as there justifiably should be, to climate change and sea level rise and its impact on the coast,” said Marc Draisen, executive director of the Metropolitan Area Planning Council, which released the new analysis. “But we also have to pay attention to inland areas, to flooding from rivers and streams, to flooding that may affect previously filled land, to flooding in inadequately protected environmental justice communities.”
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On March 29, 2010, Barack Obama issued a major disaster declaration for seven counties in the state, including Worcester County, where Chaffin lived. That declaration made it possible for more than 37,000 residents to file flood claims to FEMA, resulting in much needed aid, and a unique opportunity to gather data about flooding that do not usually exist.
In the new analysis, titled “Water, Water, Everywhere: The Increasing Threat of Stormwater Flooding in Greater Boston,” experts from MAPC got access to Federal Emergency Management disaster-relief claims from Greater Boston that are not typically made available. They found that 96 percent came from outside of FEMA’s Special Flood Hazard Areas — places not considered vulnerable to floods.
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The authors say this has wide-ranging implications for an increasingly warming planet, underscoring the need for more transparency about the flood history of homes, funding for homeowners to make their properties flood-ready, and greater access to federal flood claim data.
“We found that most officials and residents were unprepared for the widespread flooding that occurred,” said Anne Herbst, a principal environmental planner at MAPC and an author on the report. “This also means that almost all the flooding occurred in areas not covered by flood protection regulations.”
Already, the nature of storms in Massachusetts has changed. From 1901 to 2016, the number of intense, two-day storms increased by 74 percent, and the heaviest rainstorms of the year now dump 55 percent more precipitation than in the mid-1900s, according to the MAPC analysis.
And it’s going to get worse.
By the middle of the century, the state could see between 8 and 10 additional days of heavy rain — defined as one inch or more — up from an average of 7 days in the years from 1971 to 2000, according to Resilient MA, a state clearinghouse of climate effects. The state’s 2022 climate assessment, meanwhile, found that damage to inland buildings from heavy rainfall and overwhelmed drainage systems was one of the biggest risks Massachusetts faces from climate change.
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Herbst and her coauthors concluded there wasn’t any one factor that could easily predict if a home was at risk of flooding, but there were some indicators that seemed to make it more likely. Those included being built within the 100- and 500-year flood zones — meaning they have a 1-in-100 or 1-in-500 chance of flooding in any given year; being built between 1940 and 1980; on flat elevations or sandy soils; or being near water, wetlands, or filled wetlands.
Emily Norton, executive director of the Charles River Watershed Association and a Newton city councilor, said the findings about wetlands were particularly concerning because so much of Greater Boston was built on filled wetlands and many people are not aware of the vast system of underground streams below them.
“With climate change changing our precipitation patterns, we have an entire massive infrastructure that the vast majority of us never thinks about,” said Norton, who was not involved in the MAPC report. “We don’t think about the underground streams, we don’t think about the filled-in wetlands.”
In the analysis, the authors wrote that the link between filled wetlands and flooding appeared clear. When they compared a historical 1892 map of Newton wetlands with the location of flood claims in 2010, they found clusters of flood claims on former wetlands that were filled in long ago but are not included on official flood maps.
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Most planners rely on FEMA flood maps for decisions about where to build. But those maps have been criticized for failing to keep up with changing patterns due to heavier rains.
“They’re nowhere near up to date with the precipitation that we know is already here, and coming,” Norton said.
The MAPC authors used Woburn as a case study, interviewing 44 residents about the 2010 floods. Ninety percent said they had groundwater seep up through their basement floors.
“We found that very few residents had prior knowledge of their flood risk,” the authors wrote. “This is perhaps not surprising as almost all the interviewees live outside the 1% and .2% chance flood zones — locations identified on FEMA maps as areas of ‘minimal flood hazard.’ ”
In the interviews, Woburn residents described severe anxiety during heavy rains and the financial toll from the flooding.
The authors of the analysis said they are hoping it will help policy makers as they consider the threat of inland flooding. The analysis featured several recommendations, including more widespread access to federal flood claim data, so further analysis can be done; better incorporation of flood data into planning projects; and legislation that requires a property’s flood history be disclosed to potential buyers. Massachusetts is one of 15 states that does not have such a requirement.
They also hope it could inspire a proactive take on how to make homes in the state more prepared for a future in which floods could happen seemingly anywhere.
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“We have this challenge of figuring out how to retrofit properties on a home-by-home basis,” said Tim Reardon, the data services director at MAPC and an author of the analysis.
The Chaffins, meanwhile, moved out in 2016. Even after years of work, replacing the walls down to the studs and then running dehumidifiers 24/7, there were traces of the flood. “It still smelled like mold down there,” Casey Chaffin said.
Now, she looks back on the event as a warning from a warming planet, as if from a fed-up mother who has had it with bad behavior, slowly counting to the big consequence — “one . . . two . . .”
“My feeling in the moment now with climate change? Scared,” Chaffin said. “I wonder how close we are to hearing her say ‘three.’”
Sabrina Shankman can be reached at sabrina.shankman@globe.com. Follow her on Twitter @shankman.