How Clean Is the Hudson River?

The Answer Can Change From Pier to Pier

By Brennan LaBrie

In April, the New York State Department of Health (DOH) announced that New Yorkers could eat some fish from the Lower Hudson River for the first time in 50 years. It marked a milestone for a river with a toxic reputation and an infamous designation as the country’s largest Superfund site. But many New Yorkers still view the murky river with skepticism. After all, the state says you can eat fish from the river, but should you? And is it safe to spend time on the water — or even swim in it?

The answer, it turns out, depends on where and when you go. A public water quality database compiled during warmer months by a citywide network of researchers and volunteers can help you make your decision.

The Community Water Quality Testing (CWQT) project launched in 2011 in response to requests for timely water quality data from kayakers, boaters and other people who use the river. Existing databases showed a steady decline in chemical pollutants in the water thanks to actions like the 1972 Clean Water Act and a major cleanup by the Environmental Protection Agency. But those heading out onto the river were dealing with a more immediate concern: sewage contamination. “They’d take people out on the water and it would smell like sewage, and it would look like sewage,” said Cody Herrmann, program coordinator for CWQT. The testing they requested from the state could take months, she said. “The state and other agencies are doing really important large-scale, long-term research, but that’s not as helpful to someone who wants to go kayaking this weekend,” said Siddhartha Hayes, manager of research and aquaria at Hudson River Park Trust.

The Trust’s River Project team is one of 12 groups spanning nonprofits, colleges and even a high school — as well as community volunteers — that gather weekly water quality data from May to October. They collect samples at about 100 sites ranging from the Hudson River to the Gowanus Canal and Flushing Creek and test them for enterococcus bacteria, an indicator of fecal contamination. Results are posted on a public spreadsheet and shared in a newsletter every Friday during the recreation season.

The Hudson River Park team takes samples at six spots along the park’s four-mile shoreline and four in Hoboken. A team from John Jay College, led by Dr. Sandra Swenson (from John Jay College has been testing the Hudson River’s water for the past two decades) and her environmental science students, collects samples from Piers 84, 96 and 99 in Hell’s Kitchen.

Over the 20 years she’s tested the Hudson’s water, Dr. Swenson said the river has become “undoubtedly much cleaner.” It’s certainly better than the Hudson of her childhood, which she said was filled with “cars, gunk and all sorts of debris.”

These days, the Hudson River is “actually quite a healthy body of water,” said Tina Walsh, vice president of partnerships and engagement at the Hudson River Park Trust. Seahorses are among the aquatic species that have rebounded in the river and are now thriving, according to Walsh. “They’re very sensitive to pollution and to water conditions, and they’re seen as one of our top species every year in our survey,” she said.

Our local stretch of the Hudson is far downstream from where General Electric dumped more than a million pounds of toxic PCBs (polychlorinated biphenyls) in the mid-20th century. While the legacy contamination remains a concern, PCBs accumulate primarily in sediment and fish, making eating contaminated fish a greater exposure risk than casual contact with the water while kayaking. If anything, we’re seeing a slight increase in fish abundance, which is kind of wildly at odds with almost every large-scale vertebrate biodiversity survey,” Hayes said.

The river’s murky appearance alone doesn’t reveal whether the water is contaminated. Walsh said, “It’s always been green, brown and murky.” This is caused by a thick layer of mud on the river’s floor getting stirred up by powerful currents that move both ways, she explained. Phytoplankton add a green shade to the mix. But while the river thrives as a whole, its water quality fluctuates wildly at the local level due to spikes in enterococcus bacteria, which comes from the intestinal tracts of humans and animals. “It can even change from pier to pier,” Walsh said.

For example, on September 10, Pier 96 had a reading of 10 “most probable number” (MPN), an acceptable level of bacteria according to DOH standards. Meanwhile, the Pier 99 boat launch, just a stone’s throw away, had an “unacceptable” reading of 199 (anything above 104 is a red flag). Across the river in Hoboken that same day, one reading came back above 24,196 MPN.

Rainstorms are usually behind spikes in bacteria levels, as the city’s sewer system, which combines stormwater runoff and sewage, fills up quickly and releases overflow into local waterways. Even a tenth of an inch of rain an hour can overwhelm the 150-year-old system, Herrmann said. Leaking septic systems, sewage discharge from boats and even bird droppings can cause bacteria spikes too, Dr. Swenson added. Microplastics and floating trash can also enter catch basins and wash into the river.

On July 30, Pier 96 had an especially bad day of its own, hitting 8,704 MPN. The good news is that testing spots along Hudson River Park often register below 10 MPN. This stretch of the Hudson is a tidal estuary, where the tide changes approximately every six hours, helping to dilute enterococcus bacteria and flush them out of the system, often within 36 hours, according to Hayes. Smaller, more confined waterways like the Gowanus Canal typically have much higher bacteria levels.

An accidental splash is different from swallowing river water, according to Dr. Swenson. “The bacteria contaminated water isn’t going to cause serious harm, but if it’s ingested it can be very problematic,” she said. But if the water contains high levels of bacteria, does that mean you should think twice about eating fish caught in it? Not necessarily. “Pathogens have nothing to do with how safe the animals are to consume,” Hayes said. “Fish and other wild animals eat dead and rotting things constantly.” The threat to fish eaters comes from PCBs and other man-made toxins that have accumulated in the fish’s flesh and can be passed on to us.

Dr. Swenson has caught and eaten striped bass from the Hudson, which spend much of their lives out in the Atlantic Ocean, and said they’re “delicious.” She personally favors less fatty fish, which tend to accumulate lower levels of PCBs.

Under the DOH’s updated guidance, New Yorkers can eat certain fish from the Lower Hudson River, although limits vary by species and who is eating the catch. For example, the general population can eat up to four meals of striped bass a month, while people who may become pregnant and children under 15 are limited to one. The state advises everyone to avoid eating carp and smallmouth bass altogether.

The state also permits the general population to eat limited amounts of blue crab meat but advises people in sensitive groups not to eat it. Everyone should avoid consuming the crabs’ internal organs and cooking liquid, where contaminants can accumulate. For the full list of species, consumption limits and preparation precautions, see the DOH’s Lower Hudson River fish advisory table.

Kayaking conditions can change after rain, while the safety of a fish meal depends on the species and who is eating it. But what about swimming? Water quality is only part of the equation. The stretch of the Hudson along Manhattan is classified for “secondary contact” recreation, such as kayaking, rather than “primary contact” activities like swimming.

Even when bacteria levels are low, strong currents and heavy boat traffic present additional risks. The New York State Department of Environmental Conservation warns that both factors, along with changing weather and submerged hazards, need to be considered when swimming outside designated bathing areas.

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Originally published in W42St.