Lily Maxwell
Peering at New York City’s landscape more than 400 years in the past — when the marshes, ponds and streams crisscrossed our string of islands — can help planners and policymakers better understand the city’s flooding future.
Researchers at the New York Botanical Garden looked at where water used to be, where there’s water now and where — thanks to climate change — water will be in the coming years. Those places are called Blue Zones.
The five boroughs contain more than 500 of them, according to a new paper published Wednesday in the Annals of the New York Academy of Sciences, the first comprehensive analysis of its kind. The Blue Zones cover more than one-fifth of New York’s land.
“Everybody was startled, including us, that it’s more than 20% of the city,” said Eric Sanderson, vice president of urban conservation at the New York Botanical Garden and an author of the paper. “That combination, you can’t really argue with it — places that were wet, are wet and will be wet in the future.”
Lucinda Royte, lead author of the paper and manager of urban conservation, data tools and outreach at the New York Botanical Garden, said the Blue Zones indicate where it’s most pressing to address flood risks and increase resiliency.
“It can be a pretty good guide about where we’ll see flooding in the future as a result of coastal flooding from storm surge and sea level rise, and inland flooding from rainfall events,” Royte said. “It can help us plan a little bit better about where we need to make some infrastructural changes in the city before a flooding crisis happens.”
About 1.2 million people (about 12% of the city’s population) and 11% of buildings are in Blue Zones. With the report, the Botanical Garden launched a digital tool that shows block-by-block information about historical ecology, current flood vulnerability and future flood risks.
Both LaGuardia Airport and JFK Airport are located in Blue Zones, on former salt marshes and marine ecosystems that were filled in. About a third of public housing developments, home to some of the poorest New Yorkers, are in Blue Zones, too.
Royte herself lives in a Blue Zone: Gowanus, Brooklyn, which was historically a salt marsh with Gowanus Creek flowing through. The concept of Blue Zones hit home for her when Hurricane Ida brought floodwaters to her neighborhood.
“My entire block was underwater,” she said. “I saw ponds and streams and wetlands return.”
Notably, the paper notes that some of the Blue Zones will become uninhabitable in the future, which points to the urgent need to build more housing, transit and other services elsewhere in the city — a conclusion other studies have made.
‘Water Doesn’t Care’
Blue Zones raise a red flag about the scale of the flood problem New York City faces, and will face, thanks to climate change, which promises to bring higher seas, more intense storms and more rainfall in the coming years.
“It shows how large scale this is and it lets you look at the city as a landscape,” Royte said. “We currently view the city through its political boundaries. We care about neighborhoods and zip codes, but water doesn’t care about those boundaries.”
Of the Blue Zones, nearly two-thirds of the land area is at risk of coastal flooding from storm surge and sea level rise. About 5% of the Blue Zone land is at risk of flooding from rainfall, and 36% could see both coastal and rainfall flooding.
Much of the land in the Blue Zones is public, with government entities owning about two-thirds and the Department of Parks and Recreation specifically overseeing half of that.
“It’s so obvious that investing in parks will save lives and livelihoods,” said Amy Chester, director of Rebuild By Design, who reviewed the Blue Zones paper. Her organization last year released an analysis showing a majority of city parks will be at risk of flooding.
The Parks Department — whose proposed budget falls short of what Mayor Zohran Mamdani had promised — acknowledged its role in flood management.
“By working together and integrating the latest data and best practices into our planning process, we can create a stronger, more equitable park system that protects both people and nature for generations to come,” Parks spokesperson Judd Faulkner said in a statement.
In a statement, DEP spokesperson Doug Auer called the Blue Zones analysis “a useful tool in our collaborative stormwater planning efforts,” and pointed to work the agency is doing with other agencies to “identify where public lands can serve double duty for stormwater management and help restore natural urban drainage corridors.”
Many of the initiatives to make neighborhoods more resilient to flooding — including permanently moving people away from risks, adding storm drains and building rain gardens — are in the works, prompted by disastrous flooding after 2012’s Hurricane Sandy and 2021’s Hurricane Ida.
“We found, coincidentally, when you look at places that flooded during Hurricane Sandy or Hurricane Ida, they line up pretty closely with historical hydrology,” Royte said.
The storm surge of Sandy flooded areas that had been beaches and tidal marshes, while Ida’s deluge flooded places that had been ancient ponds, wetlands and streams.
Residents of Hollis, Queens, dealt with devastating flooding during Ida as well as during many other rainstorms, and learned their lowlying neighborhood was built atop a former pond.
The Hole, a neighborhood on the border of Queens and Brooklyn that sits below sea level, has continuously taken on water that can remain days after it rains. The city is now offering possible buyouts to residents there.
In The Bronx, the city is also working to unearth Tibbetts Brook in order to bring the subterranean waterway above ground, as it was over a century ago. That way, the brook can once again channel water, preventing it from hitting the sewer system and surrounding areas.
But Sanderson said more must be done: “I don’t think there’s any choice but to scale up. The climate is going to force our hand, and we’re already seeing that,” he said.
“You can use planning and ecosystems to help return some of that water to the sky and some to the ground and not assume all has to go through the wastewater treatment plants.”
