Report: Bacteria levels too high for safe swimming in western Long Island Sound

Fecal bacteria levels in many parts of western Long Island Sound were too high to safely swim in or wade into last summer, according to monitoring conducted by the environmental nonprofit Save the Sound.

Rivers remained the most polluted, failing 79% of the time, according to the group's report, released Oct. 31. Embayments and shoreline sites passed more than half the time, though both failure rates were up from 2022.

Trained volunteers collected samples once a week for 12 weeks from 65 sites in Connecticut, Westchester County, Queens and four sites in Nassau County.

The samples were sent to a lab for testing. Saltwater samples were tested for enterococcus, an “indicator bacteria” that is not itself harmful but points to the presence of fecal contamination and therefore possibly harmful bacteria and protozoa.

Freshwater samples were tested for E. coli, which generally causes mild stomach upset, though some strains can cause severe gastrointestinal problems.

Only one test site, in Greenwich, Connecticut, met the Environmental Protection Agency’s recreational water quality standard with every sample collected there, according to Save the Sound.  

The failure rate across all 65 sites is up 8% from last year, and up 15% from 2016, the first year the group posted failure rates. Peter Linderoth, director of water quality for Save the Sound, said some of the increase can be attributed to the addition of three new testing stations in Westchester County. Thirty-two of the 36 samples collected from those sites failed, he said.

At nine sites across the Sound, all 12 samples taken over the summer exceeded the standard.

One of these was Udalls Mill Pond in Saddle Rock.

Dan Levy, mayor of Saddle Rock, says the old tidal gristmill gate at the mouth of the pond has been broken for years, so stormwater that washes into the pond doesn’t get washed out to the sea.

“It’s standing water, and where you have standing water, chances are it’s going to get polluted.” Levy said. “No one in their right mind would go swimming there. It’s a cesspool.”

The other three test sites in Nassau were around Little Neck Bay. Martin Court, a residential street in Kings Point, had a 67% failure rate. Steppingstone Park in Kings Point had a 33% failure rate, and the boat launch in Great Neck Estates Park had a 42% failure rate.  

Sources of fecal matter in surface water include effluent from wastewater treatment plants, leaking septic systems, stormwater runoff, sewage dumped from recreational boats, and pet waste. Failure rates tend to be higher after wet days, since stormwater runoff carries contaminants into the waterways.

“Stormwater and septic systems are likely to be the two main culprits for the high bacteria counts that we found” in Udalls Mill Pond, Linderoth said. During their monitoring work, researchers spotted a ditch that rapidly fills with stormwater and empties into the pond.  

Fecal matter in waterways is harmful to wildlife as well. "Generally speaking, it's not good for animals to swim in sewage," Linderoth noted. Water contaminated with sewage tends to have too much nitrogen and low levels of oxygen. 

Next year, Save the Sound plans to do DNA testing of samples from sites that have chronically high levels of contaminants, to help them identify the sources of the fecal matter: human, canine or wildlife. 

Climate challenges

While water quality has improved dramatically from decades ago, before the Clean Water Act regulated wastewater dumping, the changing climate has brought new challenges, experts say. 

“We are getting these big rain events, where we get 5 inches in two days,” said Evelyn Powers, executive director of the Interstate Environmental Commission, a nonprofit that studies pathogens in Long Island Sound. Aging storm sewers don't have the capacity to manage the increased volume. 

And in places where stormwater and sewer water flow through the same pipes — including New York City and around Little Neck Bay — the overwhelmed system dumps untreated sewage into the nearest canal or bay. Reducing these stormwater overflows is "a true, proven way to improve water quality," Linderoth said. 

"There's an enormous need for investment in green and gray infrastructure that would prevent runoff in our waterways," Powers said, including replacing impervious streets and parking lots with porous concrete, building catch basins to hold rainwater, and bioswales to direct it to the root zones of hardy natives. Citizens can do their part as well by planting rain gardens and connecting gutters to rain barrels.  

For those looking for safe places to swim, Save the Sound publishes an annual report on the water quality of more than 200 of the Sound's beaches, assigning each a letter grade.