Nearly two years after the Gowanus rezoning’s passage, signs of change are all around: demolition projects and new builds are transforming the neighborhood. According to the Department of City Planning, roughly half of the expected 8,500 apartments along the canal are in planning or construction stages.

Adi Talwar

The Gowanus Canal in Brooklyn, where Combined Sewer Overflows (CSOs) have added to the already polluted waterway.

Last October, Gowanus neighbors gathered at the corner of Douglass and Bond streets for the second annual Van Alen block party. Among the lively mix of music and dancing was a table covered in colorful markers, stickers featuring rolls of toilet paper and sea creatures, and clear container boxes where attendees could build and decorate their own lamps.

But these were not your average lamps: inside the clear container box shell was an LED light programmed to turn on during periods of heavy rainfall.

The lamps are part of Van Alen Institute’s GLOwanus campaign. Designed as an awareness tool, the lights are a “visual siren” to reduce water consumption by encouraging people to skip out on showers and hold off on flushing the toilet where possible, an effort to mitigate the amount of sewage overflowing into the nearby canal.

“They essentially will light up when the New York City waterbody advisories web page indicates that there’s a water quality advisory alert in the Gowanus Canal,” said Steve Koller, a PhD candidate at the University of Miami’s Rosenstiel School who was part of the team of Neighborhood Design Fellows that conceived the idea for the lamps.

Van Alen hopes to distribute dozens of the new lamp prototypes to Gowanus residents and businesses this year, as the neighborhood prepares to welcome a flurry of new development. A rezoning of the community, approved in 2021, is slated to add 8,500 new apartments over the next 12 years, 3,000 of which will be affordable as New York continues to confront a housing shortage.

Once completed, approximately 20,000 new residents will call Gowanus home. Critics of the rezoning argue that influx will strain the neighborhood’s infrastructure, including the potential for more combined sewer overflows (CSO)—when the sewer system hits capacity, causing a mix of rainwater runoff and sewage to flow untreated into nearby water bodies.

To mitigate that, officials broke ground this spring on two retention tanks that, by 2035, are expected to prevent up to 12 million gallons of sewage from overflowing into the already polluted canal during storms. The city has also made various sewer and stormwater infrastructure commitments as part of what’s called the “56 points of agreement”—a list of commitments the city agreed to meet as part of the rezoning. 

The Department of Environment Protection (DEP) recently completed a $54 million upgrade on the sewer system along Third Avenue, which the Mayor’s Office claims will keep pollution and flooding at bay. More work will be needed to prevent flooding in other parts of the neighborhood though, advocates and city officials say: on July 4, a storm led to treacherous local conditions, with water filling the streets after heavy rain. 

“First and foremost, for the livability in Gowanus, is to ensure that environmental justice is prioritized here,” said Councilmember Shahana Hanif, who oversees district 39.

The city’s plans to manage CSO

Nearly two years after the Gowanus rezoning’s passage, signs of change are all around: demolition projects and new builds are transforming the neighborhood. According to the Department of City Planning, roughly half of the expected 8,500 apartments along the canal are in planning or construction stages. The tallest buildings will be anywhere from 25 to 30 stories.

The majority of New York City’s sewage system is combined, meaning that it captures both sewage and rainfall. When there’s a storm and the sewage system reaches capacity, it ejects the contaminated water into local waterways. This phenomena has reared its ugly head in summers past, when beaches have been forced to close as a result of poor water quality.

There are 11 active CSO outfalls and three stormwater outfalls that discharge into the Gowanus Canal. This flow of contaminated water, combined with decades of toxic waste disposal from bygone factories, explain why the canal is so notorious for pollution; the waterway was declared a federal Superfund site in 2010.

According to the final environmental impact study, the city expects that the rezoning will result in approximately 1.29 million gallons of additional wastewater per day. But government officials and community groups say plans and laws are in place to deal with this. 

Last year, the City Council passed the Unified Stormwater Rule, which mandates new developments in the city—including those that are part of the Gowanus rezoning—must have stormwater and sewage management infrastructure on site. According to the impact study, this is expected to reduce overall CSO into the canal as development occurs over time.

“The Unified Stormwater Rule benefits in the Project Area more than offset the increase in sanitary flows,” the environmental impact study reads.

But some have questioned those numbers. During the public review process for the rezoning in 2021, U.S. Rep. Nydia M. Velázquez called the city’s environmental impact statement “fraught with inconsistencies and contradictions,” saying it used outdated rainfall data that didn’t account for heavier downpours, like those seen during Hurricane Ida, which have increased due to climate change.

City officials say the two retention tanks planned for the canal will help address those capacity issues during storms by diverting contaminated water during periods of heavy rainfall.

In March of this year, Mayor Eric Adams announced that his administration and the U.S. Environmental Protection Agency finally broke ground on the first of the underground sewage overflow tanks, required by a federal order as part of the canal’s ongoing cleanup.

The construction starts after a number of delays around the project. But the rezoning’s points of agreement includes a pledge that the city will comply with the EPA’s timeline for the tanks, and a task force formed last year will be monitoring that progress. 

The first of its kind, the task force is broken up into five different committees that work to advance the city’s rezoning commitments, and hold agencies accountable for delivering on them (critics, though, have pointed to the failures of similar agreements around past land use deals that never came to pass).

Comptroller Brad Lander, who previously served as councilmember for district 39, attended an oversight meeting for the task force in June and was impressed with what he saw. “I was really quite encouraged by how many of the different points of agreement are moving forward,” he said. 

“What we’re seeing here has not been done before,” commented Hanif.

The first retention tank will hold up to 8 million gallons of combined sewage during rainstorms, while the second up to 4 million gallons. Together, when fully built, they are estimated to reduce overall CSO volume by about 160 million gallons per year.

Koller, the PhD candidate, thinks that the tanks are necessary, but emphasized that they’re not the silver bullet for a problem that’s been plaguing Gowanus for years. Data from the city’s Department of Environmental Protection (DEP) in 2008 put the estimated CSO output into the canal that year at 377 million gallons; a more recent mapping of CSO outputs along the canal by Open Sewer Atlas NYC shows closer to 250 million gallons as of 2016.   

“Even by 2035 with these billion-dollar scale investments, we still don’t have line of sight on zero CSO into the Gowanus Canal,” Koller said. “We’re still looking at 100 million gallons [of CSO] per year.”

Adi Talwar

A Combined Sewer Overflow point at the Southeast corner of the Carroll Street Bridge over the Gowanus Canal.

Community skepticism

Local advocacy group Voice of Gowanus has been a vocal opponent of the rezoning. In 2022, they filed a lawsuit claiming that the city skirted certain relevant environmental laws as part of the rezoning process. The Kings County Supreme Court dismissed the lawsuit in July 2022. The case is now pending appeal.

One of the group’s main concerns is that the CSO retention tanks won’t have enough capacity as more and more people move into the neighborhood.

“I mean, honestly, where are the feces going to go?” said Linda LaViolette, a longtime resident of the neighborhood and member of Voice of Gowanus. “You know where it’s going? It’s going to go in the canal.”

The original call for the tanks dates back to 2013, when the EPA issued a “Record of Decision” for the Gowanus Canal Superfund Site. 

Christos Tsiamis, an engineer and the former remedial project manager for the Gowanus Superfund site, was in charge of calculating the sizes of the CSO retention tanks. At a June 2022 Gowanus town hall meeting, he admitted that when he calculated those volumes, he did not consider all the new high-rise buildings that might go up in the neighborhood in the succeeding years.

“Our [tank] design did not take into account this kind of development,” he said, referring to the rezoning.

This was one of the driving forces behind Voice of Gowanus’ recent complaint which prompted the EPA Office of Inspector General (OIG) to step in. Their audit, which is already underway, will investigate the status of CSO tank construction at the Gowanus Canal Superfund site. A representative from the OIG office said they expect to issue the audit by the end of this year.

Voice of Gowanus in early July sent a request for a “Sewer Hookup Moratorium” to EPA Region 2. The letter calls for a pause in new hookups until the city takes a number of steps to stem pollution of the canal. 

Other community members and officials interviewed by City Limits, however, expressed their support for the rezoning and applauded how it integrates environmental priorities. 

“This was one of the most successful community advocacy efforts on a rezoning across the city,” said Andrea Parker, executive director of the Gowanus Canal Conservancy, which advocates for green infrastructure around the canal.

Parker pointed to the comprehensiveness of commitments outlined in the “points of agreement” and the creation of the Gowanus Oversight Task Force as victories worth celebrating.

Eric McClure, chair of Community Board 6, said he recognized the issues with the canal and surrounding upland sites, but that he is still in favor of the rezoning and its CSO goals. 

“Now, the science is better. The engineering is better,” said McClure. “I am confident that this work will be done properly.”


The city has set 2035 as the target to meet the goals of the rezoning. Developers originally expressed worry that a deadline for a now-expired tax abatement program, 421-a, could put certain projects that are part of the rezoning on hold. 

“If those projects don’t get developed, then the brownfields don’t get remediated, the affordable housing doesn’t get built, and those affordable artists studios also don’t get built,” said Michelle de la Uz, executive director of the Fifth Avenue Committee

However, Gov. Kathy Hochul announced a workaround earlier this month in which the state would allow developments to qualify for a tax break with benefits akin to those offered through 421-a. 

As far as the CSO tanks, the EPA’s timeline suggests that the 8 million gallon tank will be completed in 2029 and the 4 million gallon tank will be completed in 2028. While that might seem far away, Parker from the Canal Conservancy says the city is moving fast relative to other water body projects.

“They’re moving in line with the EPA’s timeline,” she said. “They’re moving forward.”

The city comptroller agrees. While residents might not be able to reap the benefits of the new sewage and stormwater infrastructure right away, it’ll be worth the wait, he said.

“The realization of many of the benefits of the rezoning and the points of agreement in all likelihood are going to take somewhat longer than we want them to take,” said Lander. “But we’re building a community here for decades to come.”