Opinion: When It Comes to NYC’s Waterways, Don’t Let Oysters Do All the Dirty Work

“There’s something admirable about trying to restore life in the places that need it most. But without pairing those efforts with real investment in pollution control, especially wastewater infrastructure, we’re asking oysters to succeed in conditions that science says they can’t withstand long-term.”

When I first learned about oyster restoration in New York Harbor, I was amazed. These small, craggy creatures could filter water, support biodiversity, and even help stabilize shorelines. With over 150 million oysters already introduced by initiatives like the Billion Oyster Project, it felt like a rare climate success story.

I volunteered with the organization, helping monitor oyster research stations, collecting data on biodiversity and growth, prepping shell piles on Governors Island, and tying knots for cages. I spent time watching the mud crabs and (perhaps a little too enthusiastically) squeezing sea squirts like glorified ocean stress balls. It was hard not to be inspired. These reefs weren’t just theoretical solutions. They were alive, and they were bringing the harbor back with them. But what I’ve come to realize is that they’re also incredibly vulnerable, and we rarely talk about that. 

New York City’s sewer system is over a century old. In much of the city, stormwater and sewage still flow through the same pipes. When it rains, even just a 10th of an inch in an hour, the system overflows. These combined sewer overflows (CSOs) happen around 90 to 100 days a year, releasing an estimated 27 billion gallons of untreated waste directly into local waterways. That’s the water oysters are expected to filter.*

In theory, that’s part of their job. Oysters are filter feeders, capable of processing up to 50 gallons of water per day, removing particulates, bacteria, and excess nutrients. That’s why oyster restoration is framed as a nature-based solution to urban water pollution. But in reality, these systems can be overwhelmed, and increasingly are, as climate change makes heavy rainfall and flooding more frequent.

CSOs flood estuaries like New York Harbor with a slurry of freshwater, debris, heavy metals, bacteria, and nutrients. They lower salinity, increase turbidity, deplete oxygen, and introduce a mix of pathogens and pollutants. For oysters, this isn’t just unpleasant, it’s dangerous. Research shows that exposure to CSO-related stressors can impair oyster shell growth, weaken their immune systems, and disrupt the microbial communities that help them process pollutants. In some cases, they may even stop filtering altogether, temporarily closing their shells in response to poor water quality.

And yet, despite these limitations, oyster restoration is often presented as a silver bullet, “living infrastructure” that will clean our waters and buffer our coasts. It’s a compelling idea and I understand the appeal. But we have to ask: what do we owe to the systems we’re asking to protect us? 

Because the truth is, many restored reefs are being placed into waters that are still fundamentally polluted. High-profile restoration zones like Jamaica Bay, Newtown Creek, and the Gowanus Canal are also among the most heavily affected by CSOs. Newtown Creek alone sees an estimated 1.2 billion gallons of sewage overflow annually. 

There’s something admirable about trying to restore life in the places that need it most. But without pairing those efforts with real investment in pollution control, especially wastewater infrastructure, we’re asking oysters to succeed in conditions that science says they can’t withstand long-term.

That’s not to say the people running these projects don’t understand the risks. They do. Establishing a reef takes years of planning, monitoring, and permitting before a single oyster is deployed. At the City Island Oyster Reef, for example, teams spent years conducting fish surveys, measuring biodiversity, and assessing habitat conditions, and only now are they nearing the point of installing their first actual reef. Even after installation, these reefs require continued maintenance and oversight. They are not self-sustaining, not yet. 

But public narratives often simplify this. Reef openings get press coverage. Infographics tout the filtration power of a single oyster. But what doesn’t always get communicated is that oysters don’t scale overnight. They don’t filter through floods. They don’t fix what we refuse to.

And that’s where the real tension lies. When restoration is presented as a climate solution without the necessary structural reforms, we risk falling into what economists call a moral hazard: the assumption that something (or someone) else will absorb the consequences of inaction. In this case, the oysters become the stand-ins. We ask them to filter the byproducts of climate change, outdated infrastructure, and political delay. Not because it’s the best strategy, but because it’s more visible, more fundable, and more palatable than systemic reform.

This isn’t an argument against oyster restoration. I believe deeply in its value. The ecological and educational returns are real. The harbor is healthier today than it was decades ago, and these reefs are part of that progress. But we need to be honest about what oysters can (and can’t) do. They can’t prevent raw sewage from flooding their beds 100 times a year. They can’t keep filtering through hypoxic dead zones. And they can’t build resilience on their own. 

If we want to treat restored reefs as infrastructure, we have to treat them like infrastructure, not symbols. That means investing in both gray infrastructure (traditional systems like upgraded sewer lines and stormwater tunnels) and green infrastructure (natural solutions like rain gardens and permeable pavement that help reduce runoff at the source). It means ensuring that restoration is not a substitute for reform, but a partner to it.

Why does this matter beyond oysters? Because clean water isn’t just an ecological goal, it’s a public health necessity. Contaminated waterways can harm vulnerable communities, spread disease, and degrade the urban environment for everyone who lives near it. We can’t build climate resilience on symbolism alone.

There’s nothing wrong with celebrating progress. But we can’t mistake visibility for resilience, or inspiration for immunity. Oyster reefs show us what recovery might look like, but only if we stop asking them to filter out everything we haven’t yet faced.

Audrey Li is a Scarsdale High School student who volunteers with oyster restoration projects in New York Harbor and Long Island Sound. 

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*Editor’s note: After publication, the city’s Department of Environmental Protection noted that some figures included in this op-ed were outdated, and shared newer statistics that reflect improvements in local water quality as a result of the city’s Long-Term Control Plan to reduce Combined Sewer Overflows (CSOs). The city’s sewer systems can handle approximately 1.5 to 1.75 inches of rainfall per hour, according to the DEP, and annual CSO volume is now closer to 18 billion gallons per year, according to the state’s Department of Environmental Conservation, not 27 billion. DEP pointed to other improvements in water quality metrics, including declining bacteria levels: last year, for example, fecal coliform levels hit their lowest point since 2017, and enterococci levels were the lowest recorded since 2014. Wildlife such as dolphins, seals, sea turtles, sea horses, whales, ospreys, and bald eagles have returned to New York Harbor, which a DEP spokesperson described as “clear signs of a thriving marine ecosystem.”