A survey conducted in July on three Thorne lakes has found them to be clear of the invasive Eurasian milfoil plant that has been found in some waterways of neighbouring Otter Lake.
The Thorne Lake Home Owners’ Association (TLHOA) hosted biologist Annie Parent on July 21 to test for the plant on Thorne, Long and Killoran lakes, who found no trace of it.
“We were really, really happy, because it is really hard to get rid of,” said TLHOA president Judy Hancock about the result.
Eurasian milfoil is a common invasive species that is easily spread either by introducing unwashed boats with traces of the plant into new bodies of water, or by boat propellers chopping up pieces of the plant and spreading it.
“[It] takes the place of indigenous species, so it’s a danger to the biodiversity of a lake,” said Parent, who is not an expert in milfoil but has seen its impact in her career as an aquatic biologist.
She said the plant chokes out other indigenous life in the lake to the point where nothing can outcompete it. “Invasive exotic plants, they have nothing to prevent them from reproducing. There are no controllers,” she said.
A 2023 survey commissioned by the municipality of Otter Lake, also conducted by Parent, first flagged the presence of the plant in two of its lakes. Last year, another survey found the plant in three more lakes.
Otter Lake council has since implemented solutions to curb the plant’s spread, including closing its public boat launch on Farm Lake. Council passed a bylaw in 2020 making boat-washing mandatory before putting any craft into a new body of water.
Hancock said while the lakes her association serves do not have public boat launches, the organization still wanted to be proactive about stopping the plant’s spread.
“If it can happen to Otter Lake, it can happen anywhere,” she said of the plant’s appearance in the neighbouring municipality. “We wanted to [ . . . ] get ahead of it.”
Parent said in her experience, getting ahead of it is exactly what residents should do, especially in cases where there are no public boat launches for the municipality to police.
She said in Thorne and other municipalities that don’t have as many public launches, the introduction of new watercraft can make those lakes more vulnerable to invasive species.
“That’s what’s dangerous for small lakes that don’t have a public launch – there’s no boat washing, there’s no surveillance, there’s absolutely nothing.”
She said that milfoil, if left untreated, can become very thick on the surface of the water and hinder any kind of enjoyment of the lake, as has been the case in many lakes she has studied over the years.
“It was impossible for people to go out and bathe, there was too much [milfoil]. The big rods can wrap around your feet and it can be dangerous.”
Hancock said it is exactly this kind of thing that her organization wants to avoid. She said that by handing out flyers and ordering this survey, they hope to educate their neighbours about the risks the plant could pose for their summer havens.
“Everybody wants to make sure that they do their due diligence, because these cottages are legacy properties [ . . .] So people really want to preserve the flora and fauna. They want to preserve the air and the water so that the enjoyment can be there for their kids and grandkids,” she said.
Parent said even though the milfoil test came back negative, the work doesn’t stop there for the TLHOA – cottage owners still need to be vigilant about who is entering and exiting the water on their property and ensure they are properly cleaning their craft.
“For users who put their boat in the spring and take it out in the fall [ . . . ] they’re not going to be the ones to bring in milfoil. The family, the friends, and [ . . . ] people who allow people to put their boat in the water. That’s where the risk is.”
Hancock said she is going to communicate that message to members of her association, and is also encouraging other lake associations to do the same thing. She said she will also bring the issue to the municipality to see if there is anything it can do to raise awareness to the issue.
Parent said residents can also do routine visual checks to see if there is milfoil on the lake.
A guide created by local environmental organization Ottawa Riverkeeper offers tips for identifying Eurasian milfoil, as well as other common invasive species in the Ottawa River watershed. It can by found by visiting Ottawa Riverkeeper’s website and searching “Invasive Species in Quebec Regions of the Ottawa River Watershed.”
