Genetic testing of contaminated water that flows into Long Island Sound off Glen Cove shows that the high bacteria levels stem from animal, rather than human, waste, officials said.
City, county and state officials had theorized that residential septic systems might be responsible for the contamination that has left Glen Cove’s Crescent Beach closed to swimming and bathing for nine years.
But recent U.S. Environmental Protection Agency testing eliminates that possibility and “confirmed that there is no direct or indirect discharge from septic systems along the stream corridor,” the New York State Department of Environmental Conservation said in a statement Wednesday, referring to a stream that empties into the Sound.
Glen Cove Mayor Timothy Tenke, who announced the findings during Tuesday’s City Council meeting, said the test results and the continuing inability to prevent high levels of bacteria from entering the stream make him “more determined than ever to get a water purification system in” that would lead to the re-opening of the beach.
Last month, the Nassau County Legislature approved spending $200,000 to study the feasibility of installing a treatment system that would kill or filter out the bacteria before it reaches the Sound.
The EPA collected 16 water samples from stormwater and groundwater pipes that discharge into the stream area, the DEC said.
“The 16 samples tested did not show human DNA markers,” the DEC said.
EPA officials were not available for comment Wednesday.
A county-commissioned study released in December found that pipes near the beach were discharging water with elevated levels of coliform and enterococci — bacteria found in both human and animal waste.
The level of coliform detected in the 16 samples is “consistent with a suburban setting” and “a large population of wildlife is not necessarily needed for the amount of fecal coliform found,” the DEC reported. Crescent Beach may be more vulnerable to high levels of bacteria because it, unlike most beaches in Nassau County, has a stream flowing into it, an agency official said.
The DEC is to conduct its own DNA testing during rainy periods to confirm the EPA results. If no human DNA is detected in those tests, “the investigation is complete” and local governments must determine whether regulations can limit animal waste entering the stream, an agency official said.
The DEC had spent months earlier this year investigating whether the contamination stemmed from eight home septic systems near the beach. The DEC placed dyes in the septic systems and inserted specialized cameras into pipes to determine if the pipes led to septic systems. The tests found that those eight systems were not directly discharging waste into the stream. Officials said earlier this month that those septic systems or others could potentially be seeping waste into groundwater that travels into the stream, but the DNA test results indicate that is not occurring.