[T]he state has denied a lake association’s request to treat an invasive plant in Lake Iroquois with an herbicide after receiving a slew of critical public comments.
Environmental advocates hope the decision will set a statewide precedent for restricting herbicide and pesticide use in lakes.
Last Monday, officials with the Vermont Department of Environmental Conservation denied a permit for the herbicide Sonar to treat eurasian watermilfoil. Josh Mulhollem, environmental scientist with the DEC, said that “this is the first time in recent memory that the state has outright denied one of these herbicide applications.”
Shaina Kasper, Vermont director of Toxics Action Center, referred to the decision in a press release last week as a “groundbreaking, long-term victory for the lake, surrounding towns and a toxic-free future in Vermont.”
Eurasian watermilfoil, a rooted aquatic plant native to Europe, Asia and North Africa, is now found in over 80 lakes and ponds around the state. The plant sends up shoots with feather-like leaves, forming dense beds along shallow bays and shorelines that can impact swimming and outcompete native plants. Once milfoil infests a body of water, there is no way to eradicate it.
The Lake Iroquois Association has tried a variety of methods — hand pulling, stocking weevils and contracting divers to suction harvest the invasive — to remove Eurasian watermilfoil since it was discovered in the reservoir in the 1990s. Seeing that herbicides had been used to combat watermilfoil on other lakes in Vermont, the association decided to apply to use a pellet form of Sonar — an herbicide used on aquatic plants — in shallow areas of the lake alongside non-chemical methods, according to its permit application.
The lake association, along with the town of Williston, applied for an aquatic nuisance permit through the DEC in 2016. Melinda Scott, conservation planner with the town, said that Williston agreed to co-apply when asked by the lake association because the town, along with Hinesburg, Richmond and St. George, the other municipalities that belong to the Lake Iroquois Recreation District, manages a park on the lake.
“It’s a big issue and it has impaired the water quality, especially in the beach area,” said Scott.
Deutsch, a registered nurse and Hinesburg resident, said she found out about the application at town meeting a couple years back. As she lives along a stream that flows from the lake, Deutsch was concerned about the impact the herbicide could have on her drinking water, noting that homeowners would be advised not to water their gardens for 30 days after the herbicide was applied.
“I actually measured the distance from my well to the water, and it’s 40 feet,” she said. Deutsch added that she worried about the impact on fish populations and her dogs and other animals who drink directly from the lake.
The DEC originally issued a draft permit approving the use of the herbicide in 2017. Deutsch and other neighbors, with the help of nonprofit Toxics Action Center, organized to push back against the permit as they felt the downsides of herbicide use outweighed a temporary abatement of Eurasian milfoil.
“It is a nuisance plant,” said Deutsch, but “it’s not like it’s going to reach up from the bottom of the lake and drag you to your death.”
Their efforts paid off as the DEC decided to deny the permit after reviewing the slew of comments opposing that decision.
Mulhollem said that his department had determined that the application did not meet the permit criteria of an “acceptable risk” to other species and an overall public benefit. While the treatment would have likely improved swimming and boating, it would have impacted other aquatic plants and also would temporarily restrict use of the lake, according to the DEC’s denial.
“When weighing those against each other, we have to unequivocally be able to say that the good outweighs the bad,” he said. “And for this one, it was not clear that the good outweighs the bad.”
Additionally, the DEC felt that non-chemical options “weren’t used at their full capacity,” according to Mulhollem.
The denial says that “while requesting to control Eurasian milfoil was reasonable, the (ANR) Secretary has determined that the whole-lake use of a pesticide is not a reasonable approach to manage the species.” As Lake Iroquois has high concentrations of phosphorus that stimulate plant growth, the lake is likely to have “dense aquatic growth” even if whole-lake treatment occurred, says the denial.
Mulhollem said that while each permit application is evaluated on an individual basis, because this form of herbicide is meant to be used on the whole lake, the DEC’s decision means future permit applications of this type would also likely be denied.
The lake association plans to continue using suction harvesting, underwater mats that restrict plant growth and boater education to stop the spread of watermilfoil, according to their press statement sent in response to a comment request.
