The unprecedented rainfall that remnants of Hurricane Ida dumped Wednesday night made New York City’s climate vulnerabilities starkly visible, less than two weeks after Tropical Storm Henri broke previous rain records.
The scenes were vastly different from those from the coastal flooding in 2012’s Superstorm Sandy, which prompted high-profile protection projects focused on waterfront areas vulnerable to storm surge and sea-level rise.
The recent deluges highlight how heavy rains have been largely left out of the equation, experts told THE CITY.
“We need to rainproof New York City,” said Amy Chester, managing director of Rebuild By Design, a federal effort launched by the U.S. Department of Housing and Urban Development after Sandy.
The flooding from Ida occurred because an overloaded, century-old drainage system was not built to accommodate that much water, city officials acknowledge.
“Rainfall rates were really extraordinary and far exceeded the capacity of the system,” city Department of Environmental Preservation Commissioner Vincent Sapienza said Thursday at a briefing with Mayor Bill de Blasio and Gov. Kathy Hochul in Hollis, Queens. “Anything over two inches an hour, we’re going to have trouble with.”
The National Weather Service measured more than three inches an hour at the storm’s peak. At least 13 people died — including 11 trapped in flooded basement apartments.
Environmental advocates are calling for the city to enhance how it handles stormwater by expanding green infrastructure to increase absorption and by updating the system of sewers and pipes. Federal funds could help, but even with resources available it would take years to expand the city’s drainage capacity to handle massive weather events such as Ida.
“We’ve done a good job of thinking a lot about water coming in from the edge, but we’ve done a less good job of thinking about water coming from the sky,” said Rob Freudenberg, vice president of the energy and environment program at the Regional Plan Association.
‘Clear and Present Danger’
Ida’s downpour — more than 7 inches in all in many parts of the city — overwhelmed a sewer system already hard-pressed to handle run-of-the-mill heavy rain.
Much of the city’s network handles both waste and rain runoff in a single pipe. When rainfall exceeds the system’s capacity, starting at about a tenth of an inch of rain per hour, untreated sewage bypasses treatment plants and makes its way directly into city waterways.
Intensely concentrated rainfall adds the risk of flooding to the mix, when even the combined sewer system cannot keep up with the influx. Climate research commissioned by the city projected in 2015 that the number of days with rainfall of at least four inches would increase by as much as 67% by this decade compared to the period of 1971 to 2000.
“It’s hard to overstate on how many systemic levels this represents a clear and present danger,” said Eddie Bautista, executive director of the New York City Environmental Justice Alliance, noting that the largest combined sewer overflows are located in communities of color.
When it comes to storm drainage, he said, “We’re taking it for granted at our own peril.”
After Superstorm Sandy caused citywide devastation, the influx of federal dollars mainly went to projects to rebuild and shore up the coastline. Many of those projects are still not near completed. But preventing inundation by rain in vulnerable locations is just as important, climate watchers say.
As required under 2018 laws sponsored by then-Councilmember Costa Constantinides (D-Queens), the city Department of Environmental Protection in May released a stormwater resiliency plan, along with a map of areas likely to flood due to stormwater. Both were due in 2020 but were delayed because the COVID-induced budget crisis forced the work to pause, said Mitch Schwartz, a de Blasio spokesperson.
The plan lays out actions for the city to undertake over the next decade, from advance storm alerts for basement residents to including stormwater flood measures in the city’s climate resiliency design guidelines.
The very first item on the agenda: “Inform the public about flood vulnerability from extreme rain.”
Those warnings did not come from city officials in advance of Ida.
De Blasio on Friday said he would accelerate the timeline for implementing the stormwater plan’s measures and establish an Extreme Weather Response Task Force to develop response protocols. He asked New Yorkers to brace for the unexpected.
“This kind of radical change in weather is beyond the understanding, beyond the reach of our typical measuring tools,” de Blasio said. “Things are happening that our projections can’t track with accuracy or consistency, which means we have to assume the worst in a way we never had before.”
Planning had already been underway for years. De Blasio’s OneNYC climate and infrastructure strategies are evolutions of former Mayor Mike Bloomberg’s 2007 PlaNYC, which identified what the city would need to address flash floods and upgrade the drainage system.
Ted Timbers,a spokesperson for the Department of Environmental Protection, said the city “invests hundreds of millions of dollars annually to upgrade the entire city’s drainage system, inland and coastal.”
Separating combined sewers is in process in Gowanus, College Point and Canarsie, according to Timbers. Meanwhile, the city is investing nearly $2 billion through 2025 upgrading drainage systems in flood-plagued Southeast Queens to increase capacity and prevent inundation, as well as making headway in Staten Island, he added.
But the city has no comprehensive initiative in place or planned to expand drain capacity throughout the city to prevent flooding.
Since Ida, elected officials have been demanding more.
“We need a much more aggressive and comprehensive approach now, one that doesn’t just rely on more studies and private-sector incentives, but brings the resources, regulatory reform, implementation, and enforcement needed to make change at scale quickly,” City Councilmember and comptroller candidate Brad Lander (D-Brooklyn) said in a statement.
He referred to the stormwater resiliency plan as “utterly inadequate.”
Queens Borough President Donovan Richards said at Thursday’s Hollis news conference: “Queens needs to see much more infrastructure investment.”
“We cannot wait until tomorrow. We need it today,” he added. “These lives could have been saved if we had investment that we sorely needed a long time ago.”
A cheaper — and quicker — way to manage stormwater is through green infrastructure projects, which absorb and redirect water. These interventions include rain gardens, rain barrels, permeable playgrounds and green roofs — generally, practices that decrease impervious surfaces or divert stormwater from even entering the drainage system.
Those measures can minimize, but not fully eliminate, the effects of extreme weather, experts say.
“We need to think about a plan and an investment strategy that looks at reducing urban heat, stormwater based flooding and benefitting habitat and clean air all at once,” said Kate Boicourt, director of New York and New Jersey coasts and watersheds at the nonprofit Environmental Defense Fund. “A lot of that comes down to green infrastructure investments.”
New York City boasts more than 11,000 of these interventions, making the program the largest green infrastructure program in the country, according to the DEP’s Timbers. These include small “rain gardens,” also known as bioswales, designed to absorb excess rainwater on city streets and other public spaces.
Those programs haven’t been going perfectly: A 2019 audit from city Comptroller Scott Stringer found that out of 104 rain gardens reviewed, “the majority were not sufficiently maintained to ensure their proper functioning and appearance.” Litter and weeds plagued many sites.
Last year, the City Council voted to require certain construction projects to prevent runoff by retaining and managing stormwater on site. DEP is advancing rules scheduled to go into effect next year.
‘Water Is Our Wildfires’
Environmental advocates say the city still has a way to go.
“There’s a limit to green infrastructure, but you’ve got to at least start with that,” Freudenberg said. “Maybe it’ll capture that first inch, and then make it a little better.”
Beyond that, the city can then take more dramatic steps: Freudenberg pointed out that cities in South Korea and China have transformed lanes of traffic into canals, for example.
“Water is our wildfires,” he said. “We can use design to accommodate that.”
If Congress passes a federal infrastructure bill, New York City would be poised to receive an influx of funds that de Blasio indicated would go towards resiliency efforts.
“We’re about to make massive infrastructure investments on a scale we’ve never made before as fast as humanly possible,” he said Friday. “Then we’ll have to deploy everything the city’s got and private contractors to keep updating sewer systems everywhere, but it will be a race against time.”
A windfall for the city could fund capital investments to solve interconnected societal and environmental problems, Chester noted.
“Every single time that we go to capital projects, we should be incorporating resilience planning for flash floods, for storm surge, for heat,” she said. “Every dollar we spend will be wasted if we have to build it back again in another 10 or 20 years.”