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From her bedroom in the attic of a historic Petworth row house, Mikki Carlton can hear every storm. In the fall of 2021, when the wind screamed through the rafters and the rain pounded the roof, she knew to check the house for flooding.
That year, Carlton says, the basement flooded twice due to heavy rains and an obstructed drain. “Thank goodness” none of her roommates live in the basement, she says, but the incidents caused about $2,000 in damage, left mold in the walls, and required the purchase of a sump pump that cost about another $1,000 or so.
“It was confusing for us because we have a lot of drainages,” Carlton says. “So, it was like, why is it even flooding here?”
Many neighborhoods in the interior of D.C., including Petworth, where Carlton’s home is located, are at risk of future flooding but are missing from flood risk maps. Without map identification, Nick Bonard, a D.C. Department of Energy and Environment branch chief, says residents may not know their home is at risk for flooding or how to prepare.
The DC Flood Task Force, an inter-agency team, hopes to solve this problem by creating an integrated flood model that identifies where flooding occurs in D.C.’s interior. That information is especially important for low-income residents, who may not have the resources to bounce back from a flood, Bonard says.
“Internal flooding is something that D.C. and cities across the Northeast are, in the past couple years, just starting to understand a little bit more,” Bonard says. “And [we are] seeing more flooding as a result of the way cities were built and climate change, so it’s kind of this perfect storm.”
In March, the Flood Task Force shared that D.C. has 721 single-family homes in floodplains. The top three most impacted wards on the 100- and 500-year floodplains are Ward 6 with 190 homes, Ward 7 with 563, and Ward 8 with 185. Those wards are most at risk because of their proximity to the Anacostia River and Washington Channel, according to D.C.’s Flood Risk Map. A 100-year floodplain has a 1 percent chance of flooding in any given year, according to the National Weather Service.
The Flood Task Force is piloting its FloodSmart Homes program in these areas to help homeowners assess their properties and find feasible flood prevention measures. Some proposed measures include elevating homes on cement blocks, filling basements, and adding backwater valves. Bonard says wards 6, 7, and 8 are the starting point for preventive measures.
Justin Lini, a former Ward 7 Advisory Neighborhood Commissioner, says parts of his neighborhood are in the mapped 100- and 500-year floodplains because of their proximity to the Anacostia River. Lini’s home is located on the edge of the 100-year floodplain.
Around 2018, when Lini was an ANC, he began to pay more attention to flooding when a member of the Silver Jackets, an interagency team with representatives from the federal and local government that implements solutions to reduce flood risk, came to the neighborhood. He says he was shown projected flood modeling that displayed “alarming” flood risk to his area.
In the time since, Lini says, flooding has happened sporadically and more frequently. His street, Anacostia Avenue NE, flooded as recently as 2021, when the water level rose above his cars’ tires.
“We had people who lost cars, which seems like an inconvenience but a lot of people in my neighborhood don’t have a lot of money, and that’s how they get to work,” Lini says. “So it has a direct impact on their livelihood.”
The kind of information Lini received isn’t available to residents who live in D.C.’s interior, even though they too may be at risk of seeing significant flooding. That’s where the flood task force’s modeling and revised flood map will come in, providing scientific data to what is mostly anecdotal evidence of interior flooding in D.C., Bonard says.
A preliminary version of the map uses red circles to show where significant interior flood events have been identified. Not all of the D.C.’s interior flood events are pictured, Bonard says, and the events do not exist on FEMA floodplain maps. Those maps only show where coastal and river flooding has historically occurred.
“I think when it comes to interior flooding, one of our goals is … what is the 100-year equivalent of an interior flood?” Bonard says.
A map of interior flooding would tell residents whether or not they should consider flood insurance. Homes in high-risk flood areas, with a government-backed loan, are required to have flood insurance.
The National Flood Insurance Program, which FEMA manages, can offer up to $250,000 worth of coverage but is designed for coastal cities and houses being entirely taken by hurricanes, Bonard says. The Flood Task Force is working on strategies that make the NFIP more affordable and geared toward interior flooding.
The Flood Task Force also aims to create a model that will simulate rainstorms to pinpoint the cause of interior flooding, Bonard says. The integrated flood model will include flood data, topography, and sewer system locations. The model aims to show if a raindrop falls on the street which way it will go and into which pipe it will eventually run.
The integrated flood model will also help secure funding for projects such as the Southwest/Buzzard Point Resilience Project, which has FEMA funding. The project is piloting interior flooding solutions in the area around King Greenleaf Recreation Center on M Street SW, says project manager Andrea Limauro, due to its previous interior flooding, location on a floodplain, green space, and the need of surrounding residents. Three public housing communities are located in the neighborhood.
“As a District, we have a much bigger ability to tackle interior flood risk than riverine and storm surge risk because we have more control over right-aways, streets, [and] parks,” Limauro says.
As part of the project, areas in both King Greenleaf Recreation Center and the lowest point of Lansburgh Park will be redesigned to absorb excess stormwater. Once the extra water drains, the areas will become recreational areas again.
“The idea is to reuse mostly local parks for temporary storage of floodwaters in case you are flooded so that they’re designed to become stormwater containers, but only temporarily, and then revert back to their primary function,” Limauro says.
The earliest recorded significant flood event in D.C. was the Great Flood of 1889. The most recent of the significant floods is the Federal Triangle flood in 2006, which resulted in millions of dollars of damage to federal buildings, including the National Archives.
Bonard says the District began to pay attention to the interior flooding risk around the time of the Federal Triangle flood. In the years following, there have been a series of floods that have impacted Bloomingdale, the Cleveland Park Metro, and other areas around the city that had not been flooded before, Bonard says.
On September 10, 2020, significant amounts of rain caused interior flooding in Wards 4 and 5, sending sewage into some residents’ basements. According to a DC Water post-flash flood study, the amount of rainfall was equivalent to a 10- to 25-year storm and “the most intense in recent times.”
“South Dakota Avenue NE between Kennedy Street NE and Farragut Place NE looked like a small river after this most recent storm,” a Riggs Park blog wrote at the time.
Many homes in D.C.’s interior have high storm risk according to ClimateCheck, a tool available on the real estate website Redfin that predicts a property’s environmental risk. Dr. Max Stiefel, a climate risk data scientist for ClimateCheck, says they use extreme precipitation to represent storm risk. This measure does not include the risk of flooding that could happen in the same event.
“It’s the top 2 percent of extremely rainy days each year,” Stiefel says. “And then we sort of compare how many extremely rainy days will occur in the future based on a historic threshold.”
Alleys in Carlton’s neighborhood can become like “little rivers” during flash floods, she says. Roads near her home—Georgia Avenue NW, Park Place NW, and Sherman Avenue NW—also flood when the stormwater systems are overwhelmed and the rainfall has nowhere to drain. She once looked forward to the summer, but now she says rainstorms feel like a hurricane is coming.
The integrated flood model will one day show which interior neighborhoods, such as Carlton’s, are most vulnerable to flooding. The model and related projects are still two years away from completion. The DOEE is still gathering data and needs time to design and engineer the projects.
“If it rains now, we’re down for the count,” Carlton says.