Have you heard about milfoil — the invasive water plant that threatens Laurentian lakes? In Québec, more than 40 lakes in the Laurentians are already affected. So far, lac Manitou remains milfoil free. Let’s keep it that way! Recognition is key to prevention.
What Is It?
Eurasian water-milfoil is a highly invasive aquatic plant native to Europe, Asia, and North Africa. It forms sprawling colonies near the water's surface, shading out native aquatic vegetation and disrupting the ecosystem.
It reproduces mainly through fragmentation—even a tiny segment can drift, take root, and multiply elsewhere.
What kind of damage does it cause?
Biodiversity loss: The plant outcompetes native aquatic species, reducing plant diversity and habitat complexity.
Oxygen depletion & eutrophication: Dense mats block sunlight, stunting native plants. When they die, their decomposition depletes oxygen, damaging aquatic life and accelerating lake aging.
Recreation disrupted: Thick growth obstructs swimming, boating, and fishing. It entangles propellers, paddles, and fishing lines.
Property value: Lakes infested heavily by milfoil are less appealing—potentially lowering real estate values.
What Can We Do to keep milfoil out of lac Manitou?
1. Recognize, monitor, report.
Learn to identify Eurasian water‑milfoil: long, branching stems with feather‑like leaves arranged in whorls (usually 12+ leaflet pairs). Plant identification apps can help. Find a list of recommended plant identification apps here.
If you find milfoil, use Quebec’s invasive species reporting tool, Sentinelle, to share alert the province. This post includes more about Sentinelle.
2. Prevent spread
Wash boats before launching on lac Manitou. Inspect–Drain–Clean–Dry any boats, paddles, motors, and equipment moved between water bodies.
Avoid infested zones—steer clear of marked areas or visible mats,
Do not move water, mud or anything else between lakes.