CASTLETON — A debate about the health of Lake Bomoseen has swelled in several Rutland County towns, with residents and leaders disagreeing about the impact of an invasive weed and a proposal to control it with herbicides.
Eurasian watermilfoil, commonly called “milfoil,” is a feathery aquatic weed native to parts of Europe, Asia and North Africa. It has sprouted in many lakes around the state in the past several decades, including Lake Bomoseen, the largest lake contained inside Vermont’s borders at 2,400 acres.
Milfoil can block light from other native plants, eventually crowding them out. The plant can also be a nuisance for recreation and for property owners, and its proliferation in one lake can increase the likelihood that it will spread to others on the hulls or propellers of boats.
Milfoil is the most commonly occurring plant in Lake Bomoseen, according to a survey of the lake conducted in 2021. As many as 700 acres of the lake are capable of supporting the plant. Climate change is likely to create conditions, such as warmer waters, that help milfoil thrive.
Earlier this year, the Lake Bomoseen Association applied for a permit from Vermont’s Department of Environmental Conservation to expand its milfoil management plan, and it included spraying a relatively new herbicide called ProcellaCOR.
Meanwhile, a Facebook group called “Don’t Poison Lake Bomoseen” has gained more than 900 members, an online petition called “Keep Lake Bomoseen chemical free” has more than 1,300 signatures and a rally opposing the measure is scheduled for Sunday in front of the Castleton Town Offices.
The town of Hubbardton, which was originally listed as an applicant on the permit alongside the Lake Bomoseen Association, took its name off the application after residents and anglers spoke out against the plan at a meeting at the end of February.
“We’re calling for a moratorium on spraying any Vermont waters with herbicides until we can have a genuine conversation statewide as to how best to manage a way that we don’t like,” said Bob Stannard, a former state representative and lobbyist who has been organizing the movement against spraying herbicides. (Stannard also writes commentaries for VTDigger.)
People who oppose spraying have said the permit application took them by surprise, and they point to a lack of input from the public. The application said the lake association plans to begin spraying in June — but Sam Drazin, interim president of the association, said the organization does not intend to spray this year.
“The permit required us to include a timeline,” he said. “It was a proposed timeline because the permit required it. We have not made any decisions, and we will not be starting this in June.”
Drazin told VTDigger the association is holding a series of town hall-style meetings to welcome respectful public discourse and will consider that feedback before making a decision. Stannard said the association’s effort to understand the public’s thoughts is coming too late, and the organization does not appear to be operating in good faith. He pointed to the organization’s decision to hire a lobbyist.
“You don’t ask for public input after you’ve filed an application and after you’ve hired a lobbyist without telling anyone,” Stannard said.
Drazin said the lobbyist will help the association identify federal funding that could help Lake Bomoseen more generally, not to advocate for the herbicide treatment.
“This summer, we are really focused on continuing to have conversations, continuing to build consensus, continuing to learn, what are the concerns that the community has around lake health?” Drazin said.
Not an eradication project
Oliver Pierson, manager of the Vermont Department of Environmental Conservation’s Lakes and Ponds program, said state offices have been receiving a number of calls on the issue. State staff members are reviewing the application, he said, and an official public comment period would take place before it became final.
The state has responsibility for controlling and managing invasive species, which the state defines as species that are “not native to Vermont and have negative effects on our economy, our environment, or our health.”
Once milfoil and other invasives are introduced, eradication is almost impossible.
“It’s very, very difficult to eradicate milfoil once it’s in place,” Pierson said. “So these are control projects, not eradication projects.”
Pierson said the state encourages nonchemical methods of controlling invasives, and to obtain its permit, the Lake Bomoseen Association will need to demonstrate that other control methods won’t cut it.
ProcellaCOR has been applied in 10 lakes in Vermont over the past two years, Pierson said, and it has been effective at killing milfoil where it’s been applied.
“It specifically targets milfoil,” Pierson said. “It has very few, if any, non-target impacts. We do surveys before and after treatment on the plants in the lakes, and we have not seen any significant impacts after treatment of ProcellaCOR on any native plants.”
There have been encouraging studies that show the herbicide doesn’t appear to impact the insect population, he said, and the chemical is “undetectable in the waters within 48 hours of treatment.”
Still, people opposed to the measure cite a number of concerns. Some worry about the newness of the chemical, which came on the market in 2018.
“There is zero long-term data on the impacts and the effects of this chemical,” Stannard said.
“No wait-and-see approach,” he said. “That’s what we do with all this crap. We put it in the water or we dump it in the ground, and then 20 years later, we go, ‘Oh man, I guess we’ve made a mistake there, sorry about your Parkinson’s disease. Sorry about your cancer.’”
Anglers, who say Lake Bomoseen boasts a healthy ecosystem that supports a diverse, robust fishery, worry that fish have adapted to the weed, and its sudden disappearance could affect populations.
Rob Steele, longtime owner of Tom’s Bait and Tackle shop in Castleton, has helped organize the opposition movement.
“They’re claiming the milfoil has problems with recreation for boating and fishing — that’s certainly not the case here,” he said. “The boat launches are generally full on the weekends. You can’t put up another boat on the lake. There’s not really any harm being done by it.”
Anglers have told Steele that similar applications on other lakes nearby have impacted the fisheries there, he said.
According to Pierson, the state does not allow herbicide applications on more than 40% of the lake at a time. That limit should allow the fish to find suitable habitat when some of the milfoil disappears. So far, the data does not show that removing milfoil has had a negative impact on fisheries, he said, though he invites anglers to continue providing reports.
“Eurasian watermilfoil has both good and bad features for fisheries,” Pierson said. “Too much milfoil can remove all the oxygen from the water. It can impede the movement of fish. It can prevent sunlight from penetrating.”
Pierson spends time on Lake Iroquois in the summer, where the herbicide was recently applied and re-treated last year. Anecdotally, he said, it appeared the weed was gone after those treatments.
“What we hope is that that gives native plant species an opportunity to come back and recolonize,” he said.
One big-picture question, Pierson said, is what associations should do if herbicides don’t keep milfoil away after the treatment cycle ends. The state wants to see lake associations create pesticide mitigation strategies, he said, so they’re not restarting the spray cycle every few years.
Asked whether applying the herbicide reduces the chances the weed will return the following year, Pierson said the state doesn’t know. It’s something they’re watching, he said.
“That’s not really one of the management objectives,” he said. “We’re not audacious enough to think this is going to eradicate milfoil. We have a very worthy adversary there. We’re just trying to reduce or limit the spread and maintain those uses during the summer months.”
