Heavy rain hit New York City on Monday, July 14th, bringing a record-breaking rainfall of 2.64 inches within one hour, marking the second-highest amount in history. The downpour caused severe flooding, with multiple subway stations in Manhattan such as 28th Street and 96th Street submerged in water, leading to temporary suspension or delays of several subway lines. Janno Lieber, Chairman and CEO of the Metropolitan Transportation Authority (MTA), expressed on July 15th that the city needs to increase the capacity of its stormwater management system to prevent future subway flooding.
This storm brought 2.64 inches of rain to Manhattan’s Harlem district, while Central Park recorded the second-highest one-hour rainfall in history, only surpassed by the deluge caused by Hurricane Ida in September 2021, which resulted in New York City’s first-ever flash flood emergency.
During a press briefing on July 15th, Rohit Aggarwala, Chief Climate Officer and Commissioner of the City’s Department of Environmental Protection, stated that “this was one of the strongest storms that the (sewer) system has ever had to deal with.”
According to data from the New York State Mesonet, rainfall reached 4.08 inches per hour during the peak 15 minutes of the storm. However, the city’s sewer system can only handle 1.75 inches of rainfall per hour, leading to streets, subway stations, and even subway cars being flooded during Monday night’s downpour, causing disruptions and closures on lines 1, 2, 3, E, F, M, and R, leaving commuters stranded.
Aggarwala highlighted that the intense rainfall on the night of July 14th fits a pattern of brief tropical storms that have been occurring in New York City in recent years, indicating a growing frequency of extreme weather events – the city’s top 5 rainstorms all happened within the past four years.
Officials cautioned that adapting New York City’s aging infrastructure to rapidly changing climate conditions will take 30 years and require an estimated $30 billion. Aggarwala detailed recent stormwater management efforts, reducing the number of clogged catch basins from 5000 to just over 260, and collaborating with the MTA on subway flood prevention. However, some parts of the sewer system were constructed over a century ago and were not designed to handle such significant rainfall. Aggarwala said, “Pipes are designed for a certain amount of water. The actual rainfall far exceeds that capacity.”
Aggarwala mentioned ongoing sewer expansion projects in New York City, such as the Idlewild Park sewer project in Queens, which requires meaningful upgrades expected to demand a decade for design and construction. For instance, the $350 million Bushwick sewer expansion in Brooklyn will increase Knickerbocker Avenue’s sewer capacity ninefold and is anticipated to take nearly ten years.
Aggarwala estimated that the necessary upgrades to expand and enhance more vulnerable sections of the sewer system would cost $30 billion and take around 30 years with current funding levels. Currently, New York City annually allocates approximately $1 billion towards sewer and stormwater management.
However, costs are just one facet of the challenge. Aggarwala cited the federal government’s classification of New York City’s climate from “temperate coastal” to “subtropical,” stating, “Our infrastructure is designed for a climate we no longer live in, as if New York City had moved 500 miles south.”
Mayor Adams shared similar concerns, warning that the city remains at risk of extreme flooding, noting that “our sewer system is not built to handle this much water in such a short period.” Constructing the necessary infrastructure improvements “takes time and money.”
Adams revealed that the city’s emergency response measures include issuing early public warnings, activating the “flood emergency response plan,” and coordinating across agencies. He believed that these actions and public cooperation helped prevent casualties.
Adams emphasized on Tuesday, “I want to remind New Yorkers: floods can spread to streets, stairwells, and basements within minutes with little to no warning. Residents in basements, below-ground residences, or low-lying areas should take extra precautions, place an emergency kit by the door, clear entrances and plan to evacuate early if conditions worsen.”