The Municipality of Otter Lake is finalizing its application to Quebec’s environment ministry to be granted a permit to control the spread of the invasive lake weed Eurasian milfoil on its most contaminated lake.
A biologist’s survey first flagged the presence of the underwater plant on Farm Lake and Petit Lac Cayamant in 2023, and since then it has also been discovered, albeit in lesser quantities, on three other lakes in the area – McCuaig Lake, Little Hughes Lake, and Otter Lake.
The perennial plant is notoriously hard to kill. It grows profusely in the summer and dies in the fall, using up oxygen as it decomposes, choking the lake and killing native plant species and fish.
A team of biologists has since conducted more in-depth mapping on Farm Lake and Petit Lac Cayamant to determine exactly where and in what quantities the plant is growing, information that must be obtained for any permit to be granted by the province.
At this time, it is most pervasive on Farm Lake, particularly around the boat launch, the area the municipality is hoping to control by installing a large tarp-like covering along the bottom of the lake near the launch to suffocate the plant.
To do this, it needs a permit and grant funding from the province’s environment ministry.
“It’s taken some time to make it through the application but we’re finalizing it now [ . . . ] for work to begin next spring,” said Otter Lake mayor Jennifer Quaile, noting it was always clear to the municipality that given the lengthy application process, nothing substantial would be able to be done this year.
As it’s been working on a more hefty control strategy, the municipality has rolled out a few different measures over the past few years to stop the plant’s spread, including a bylaw passed in 2020 making boat washing mandatory before entering any body of water. It has also placed buoys in Farm Lake alerting users of thick milfoil zones.
Last July, the municipality shut down the public boat launch on Farm Lake because the milfoil had grown to be thick, especially near the launch itself.
“It would get caught up in the propeller of the boat and cut up the pieces and carry it to other sections and propagate there,” Quaile said.
All of these measures will continue this year.
“It’s status quo, same as we did last year,” Quaile said.
On Petit Lac Cayamant, the second lake that has already had an in-depth mapping done of the weed’s presence, the lake association has taken matters into its own hands.
“They applied last year and very quickly got approval to pull the weeds out by hand in one specific area of their lake,” Quaile said, noting this is something any lake association can do, once they have an in-depth biologist’s report. “That [technique] can be done in areas with less extensive growth.”
‘Stewards of the lakes’
Susan Desabrais, co-president of the Greater Otter Lake Residents Association (GORA) and a resident of Farm Lake, said she is on board with the municipality’s approach even if it is an extra step boat users must take.
“The biggest step was the heated boat washing, and it’s gotten people used to the idea [of washing their boats]. I know there’s some people that say, ‘I don’t want to make an appointment to go into the lake,’ but we all have to,” she said.
Desabrais said the measures are a necessary step to prevent the plant’s spread into other bodies of water.
“There’s people from other towns that could be bringing stuff up [ . . . ] and now your boat has to be washed. They’re controlling access to make sure that any boat going in this lake is washed, so that’s good,” she said.
Parc Leslie manager Shawn Myrick said Leslie Lake was found in the report to be milfoil-free, and he would like to keep it that way by requiring boat owners to present their cards from the boat-washing station before entering.
He said he is happy with Otter Lake’s approach to controlling the plant’s spread, but would like to see the Municipality of Litchfield begin enforcing boat-washing since that is where the southern part of Leslie Lake is situated.
Quaile, former president of GORA, was instrumental in raising awareness about the milfoil to the council as early as 2016, when she learned the plant had been found in lakes not far from her municipality.
“It was horrifying when I learned,” she said, adding that she began to inform herself on the topic and then took the issue to council. Now in the mayoral seat, she said restricting lake access was not a decision the municipality took without considering the long-term impact.
“We’re responsible to be stewards of the lakes and the natural beauty of this region, and we have to think long-term,” she said. “We had to cordon off the areas with buoys, and warn people and do the best we could to control the spread.”
Quaile said they are expecting the milfoil to reach peak thickness again this summer, which will likely mean closing the public boat launch once again.
“It’s short-term pain for people,” she said, but a decision she believes will be good for her municipality’s biggest asset — its natural beauty.
“Otter Lake, it’s very reliant on tourism, so it’s hugely important. And I care about protecting the waters that we have for future generations.”
The municipality will be holding an information session for residents at 10 a.m. on Saturday, June 7, where there will be an update on the milfoil situation.
Correction: May 29, 2025 This article previously incorrectly reported that Otter Lake was waiting for Quebec’s environment ministry to approve a mitigation strategy for controlling the spread of milfoil on lakes in the Municipality of Otter Lake. In fact, the municipality is finalizing an application for a permit to lay down a tarp on a portion of Farm Lake’s floor near the boat launch, where the milfoil is the most dense.
