A year-long study of the residual effects of ProcellaCOR, which the Lake George Park Commission used in two bays in 2024 to kill the invasive Eurasian milfoil, has concluded that the herbicide persists in the soils of the lake bottom longer than previous studies indicated.
“We have demonstrated that the herbicide will persist in the environment in its original form much longer than we would’ve anticipated, and that certainly opens up questions about its long-term impacts on non-target organisms,” said Dr. Brendan Wiltse, the study’s lead author and the executive director of the Lake George Association, the non-profit that funded the study.
The LGA cautioned the public from concluding from the scientific study that ProcellaCOR is unsafe.
“The LGA emphasizes that there is no evidence of drinking water, recreation or human health risks (from ProcellaCOR) based on the LGA’s current data,” a press release accompanying the study stated.
The study’s authors also refrained from asserting, unequivocably, that ProcellaCOR poses risks to the small insects that support the Lake George food web and which live in the sediments where ProcellaCOR was found to persist longer than a year.
“We’re not stating that definitely there will be negative effects as a result of the concentrations of ProcellaCOR that we observed persisting in the sediments. There’s very little information out there that would enable us to assess what the impact of this herbicide is on benthic organisms,” said Wiltse.
Wiltse did state that “the concentrations that we’ve observed exceed a certain limit – the so-called ‘no observable adverse effect’ limit for the small insects, the limit below which we could be certain there are no adverse effects of ProcellaCOR. But we can’t state with certainty that there is a negative or adverse effect at the higher levels we’ve observed. Basically, we don’t know (if there are adverse effects) and no one knows,” said Wiltse.
But, Wiltse said, “the fact that we have a known toxic substance persisting in the lake sediments should cause us all to take a step back and say, “what is the impact of this?’ Our commitment as a science-based organization is to continue to conduct and support the science that will answer this type of question.”
One of Wiltse’s co-authors, Dr. Curt Stager, Professor of Natural Science at Paul Smith’s College, stated, “There seems to be plenty of research showing that (ProcellaCOR) does what it’s supposed to do in terms of killing invasive plants in lakes. But we need more information about situations in which (ProcellaCOR) does what it’s not supposed to do. This is why our research is crucial.”
Dr. John E. Kelly III, Chair of the LGA Board of Directors, was quoted in the press release as stating, “The Lake George Association fundamentally believes that the most rigorous science should be guiding solutions and policy that impact not just Lake George, but fresh water across New York State. We are proud to be at the forefront of this new scientific research.”
Ken Parker, the chairman of the Lake George Park Commission, the state agency authorized by the Department of Environmental Conservation and the Adirondack Park Agency to treat the two bays on northern Lake George with the herbicide, said in response to the study, “we appreciate the LGA’s ongoing review of our treatment sites, which along with the Commission’s monitoring, continue to confirm the effectiveness and safety of the ProcellaCOR applications.”
The Park Commission’s executive director, Dave Wick, said, “The determination that ProcellaCOR was identified at trace levels in deeper sediment in the treatment areas, while academically interesting, largely aligns with established EPA and DEC registration findings. Like all other lakes across the Northeast that have utilized ProcellaCOR and seen unprecedented successes in managing milfoil, we remain very pleased with the excellent results of this project. Wick said the Lake George Park Commission has no plans to treat milfoil beds in other bays in Lake George with ProcellaCOR in 2026.
