This story by Aaron Calvin was first published by the News & Citizen on June 13.
Should the herbicide ProcellaCOR be deployed to fight the milfoil infestation in Lake Eden?
That was the question in the Eden Central School gymnasium on Saturday as a crowd of lake residents and others gathered to ask four experts questions about the weed’s effect on Eden’s premier recreation site.
A panel organized by the Lake Eden Association brought together experts on the substance, application and permitting of the herbicide. They extolled its upsides and outlined potential safety risks while soliciting the public’s questions.
In the summer of 2022, the association discovered the presence of milfoil, a tenaciously invasive aquatic plant in Lake Eden. They sounded the alarm ahead of Town Meeting Day the next year about the seriousness of the issue and the importance of an early response.
Left on its own, milfoil quickly grows across the surface of a waterbody while it chokes out other vegetation and provides no shelter or nutrients for local aquatic life. Association members called the lake the “economic heart of Eden” and said lakeside housing generated 21% of the town’s property tax revenue.
The town approved spending $15,000 in both 2023 and 2024 to pull the milfoil by hand, employ vegetation-suffocating blankets and use divers to vacuum it up, with a lot of help from volunteers. The lake’s robust greeter program also monitors boat traffic in and out of the lake and ensures milfoil isn’t slipping through on vessels.
Still, milfoil, a plant that fragments into small pieces that can easily take root and grow quickly, has remained difficult to bring under control.
“Despite these very aggressive efforts to eradicate this milfoil, using all available non-herbicide methods, we find that we are just slowing the process,” said Colleen Brennan, a lake association member who moderated the event.
Now the dedicated volunteers on the lake association are investigating whether to deploy ProcellaCOR — an herbicide that specifically attacks milfoil and is the only one legally permitted by the state — in shallow, difficult to treat areas of the lake.
The assembled panel included Pat Suozzi, president of the Federation of Vermont Lakes and Ponds; Michael Lew-Smith, a botanist and partner at Arrowwood Environmental retained to study the milfoil problem on Lake Eden; Brendan McCarthy, a consultant at a lake management company with experience applying the herbicide; and Olin Reed, an aquatic biologist with the Vermont Department of Environmental Conservation with local roots in the Eden area.
Each one was of one mind about the use of the relatively new ProcellaCOR: The herbicide is effective, has a minimal impact on the water and surrounding ecosystem and, though available data is limited, doesn’t appear to have any long-term consequences.
Suozzi attested to its effective use in combating milfoil epidemics on Lake Iroquois in Hinesburg and in Addison County’s Lake Dunmore.
She also argued that use of the herbicide was more cost-effective than treatment without it, and reduced pressure on volunteer efforts to manage milfoil, though other mitigation efforts would still be required, and warned that “misinformation” spread about the herbicide threatened effective action.
In their discussions of the use of ProcellaCOR, Suozzi, Lew-Smith and McCarthy all talked about how any browning or adverse effects caused to other lake vegetation by the herbicide seemed to be temporary, and they said that the chemical treatment had no long-term effect on animal life or water quality.
Lew-Smith, in particular, said that while he “hadn’t seen enough data to know everything about” the herbicide, its effect seemed limited from what he’d observed.
ProcellaCOR was first approved by the U.S. Environmental Protection Agency in 2018. It’s currently the only “actively permitted herbicide in Vermont,” according to information presented by Reed, and has been used 25 times since 2019 and in small areas of 11 lakes across the state.
McCarthy discussed the success his company has had applying it in New Hampshire and Vermont, and though he reiterated that it’s too new of a chemical to gauge long-term effects, he mostly focused on its efficacy.
Reed explained Vermont’s stringent rules for the application of herbicides in any body of water, which only allow it if there’s no non-chemical alternative available, an acceptable level of risk to the environment, a clear public benefit and a long-term management plan is developed.
Other divisions within the Agency of Natural Resources weigh in on the application process, which includes a public notice period before a final permit is issued.
Risk assessment
An internal 2022 memo published by an Agency of Natural Resources environmental scientist said that, according to its analysis of ProcellaCOR, “the potential for acute and chronic risks to fish, aquatic invertebrates, amphibians and other aquatic animals is considered low.”
But this April, the state permanently denied a permit to apply ProcellaCOR in Lake Bomoseen after a “great deal of public opposition” and united opposition on the town’s selectboard, according to the Rutland Herald.
Cynthia Moulton, a Vermont State University-Castleton professor of toxicology and ecology who formerly worked for the EPA’s pesticides division, published an editorial when the permit was first filed in 2022 claiming that ProcellaCOR “posed unacceptable risk and adverse effects to the nontarget organisms” and that “significant ecological risks alone should be enough to legally negate the permit request.”
The decision was appealed in May to the Vermont Superior Court Environmental Division, not by its original applicant, the Lake Bomoseen Association, but by an environmental engineer in Fairhaven who wanted to ensure the herbicides could continue to be used to battle invasive species in Vermont.
ProcellaCOR will be applied in Lake George in New York, but only after a May appellate court undid a New York Supreme Court decision that found the state had violated regulations regarding holding public processes when approving the permit.
The Lake George Association issued a scathing rebuke of the Lake George Park Commission, arguing the “risks of ProcellaCOR are too great to experiment with it in Lake George.”
During a question-and-answer period of the meeting, one Eden resident expressed concern about ProcellaCOR’s own admission of its environmental risks on its label. But Suozzi said that such a small amount of the herbicide is used that its effect on plants and animals will be entirely non-lethal.
Among anxiety about the potential risks of such a new herbicide was concern about what would happen to the lake if the milfoil wasn’t brought under control. Suozzi presented before and after images to demonstrate ProcellaCOR’s efficacy — a sickly green surface covered in milfoil paired with another showing nothing but clear blue water.
There was also the matter of eventual burnout among those currently devoting their time to fighting the milfoil battle without chemicals.
Read the story on VTDigger here: Eden residents hear from experts ahead of herbicide use in lake.