Eurasian watermilfoil control in Papineau Lake, QC (Photo by RAPPEL)

Eurasian watermilfoil control in Papineau Lake, QC (Photo by RAPPEL)

Nature Conservancy of Canada fights Eurasian milfoil in effort to restore Papineau Lake

May 7, 2024
Notre-Dame-de-Bonsecours, QC


Specialized divers and giant tarps prove effective arsenal against invasive species

Like many other water bodies in Quebec, Papineau Lake has been shaken by the arrival of Eurasian milfoil, an invasive plant that takes over wherever it lands, harming other plant species in the lake. Thankfully, Nature Conservancy of Canada (NCC) staff and the Kenauk Institute are rolling up their shirtsleeves to carry out control projects aimed at restoring the lake to its former pristine condition.

Originating in Asia and Europe, Eurasian milfoil can grow up to 6 metres tall below the water surface. It first took root in the Quebec portion of the St. Lawrence River in 1958, and went on to invade many other aquatic environments.

By growing in tall dense patches, Eurasian milfoil blocks sunlight from reaching native aquatic plants. Rotting plants in the water reduce oxygen levels for aquatic wildlife. The plant also poses a problem to human recreational activities, such as swimming, fishing and boating, by creating undesirable swimming conditions and threatening to tangle fishing lines and wrap itself around propellers and rudders. The plant can multiply when a stem is broken or pulled, as its fragments drift and take root elsewhere. This primary mode of spreading is known as vegetative reproduction.

How to tackle the problem? The first option involves having a diver pull up the undesirable plants manually to the surface and placed in a boat. The second option is to lay giant tarps over densely affected areas. Although Eurasian milfoil is an aquatic species, like other plants, it needs sunlight to survive.

Eurasian milfoil is present in most regions of Quebec and NCC is working to reduce the plant’s negative impact on our natural environment.

In the summer of 2022 and 2023, NCC and Kenauk Institute carried out control activities on Papineau Lake. We raised awareness among property owners so they can recognize the plant and avoid spreading it, such as by carefully cleaning their boats and fishing gear. Buoys were installed to demarcate dense colonies that boaters should avoid so as to not break the plants and accelerate their spread.

Since the start of the control project, 192 kilograms of Eurasian milfoil has been removed manually from Lake Papineau. In the summer of 2023, 3,600 square metres (25 sheets) of tarpaulin were installed to control seven dense beds of the invasive plant. This project will continue over the next several years, and the fight against invasive plants will also continue with similar projects in other severely affected regions in Quebec.  

Best practices are essential for controlling the spread of Eurasian milfoil, a serious threat to aquatic ecosystems. An effective and simple preventative measure is to avoid spreading plant fragments by cleaning boats (including engines and trailers) as well as fishing gear after each use in waters infested by Eurasian milfoil. Activities such as swimming, boating and fishing should be practiced away from the seagrass beds. Additionally, since phosphorus runoffs and the leaking of other contaminants into water bodies influence the growth of this invasive plant, reduce these risks by ensuring septic systems are compliant, avoiding the use of phosphate-containing products, and revegetating shorelines with native riverbank plants that are adapted to the environment. Everyone can contribute to preventing the spread of invasive exotic species and protecting our water bodies.


NCC thanks its water health consultant, RAPPEL, as well as its financial partners in this project: the Fondation de la faune du Québec and its financial partner the Ministère de l’Environnement, de la Lutte contre les changements climatiques de la Faune et des Parcs, the Kenauk Institute and individual donors. A special thank you to our volunteers for their help and contagious positive energy.


“These first two seasons of efforts to control Eurasian milfoil have been a success. The team hopes that in a few years’ time, the population of this invasive plant will be sufficiently reduced to ensure the lake’s health. My colleagues will be carrying out similar projects in the future. This first successful initiative was a lot of hard work, but the results are very encouraging!” – Annie Morrisseau, Project Manager, Nature Conservancy of Canada



The Nature Conservancy of Canada (NCC) is the country’s unifying force for nature. We seek solutions to the twin crises of rapid biodiversity loss and climate change through large-scale, permanent land conservation. As a trusted partner, we work with people, communities, businesses and government to protect and care for our most important natural areas. Since 1962, we have brought Canadians together to conserve and restore more than 15 million hectares, including more than 55,000 hectares in Quebec. NCC is a registered charity. With nature, we build a thriving world. To learn more, visit natureconservancy.ca.  

The Kenauk Institute is a charitable organization and the long-term custodian of the Kenauk property in Montebello, Quebec, Canada. The mission of The Kenauk Institute is to support, coordinate and supervise scientific research on the property and it’s surrounding area and to promote environmental education. Kenauk is an ideal location for our organization because of its extensive size, its uniqueness as a pristine watershed and as a wildlife corridor. The abundance and diversity of flora and fauna in combination with the properties unique history provides endless possibilities for research, education, and conservation.

RAPPEL (Regroupement des associations pour la protection de l’environnement des lacs et des bassins versants) was created in 1997 by lake associations who wanted to come together to better protect their respective bodies of water. Now in the legal form of a non-profit solidarity cooperative democratically managed by its members, the RAPPEL is carried by 350 members, including more than 160 associations and about forty municipalities, distributed in 11 administrative regions of Quebec. At the heart of the cooperative is a multidisciplinary professional team made up of specialists in biology, engineering, geomorphology, geography, and ecology technicians. The expertise of the staff aims to support the daily work of the volunteers of the associations and other actors in the protection of water. Part of its team specializes in studies and work relating to the prevention and control of invasive exotic species found in lakes and their surroundings. Among other things, RAPPEL has worked on the control of Japanese knotweed, common reed and Eurasian milfoil. For example, since 2014, the cooperative has installed burlap to control milfoil in nearly fifteen lakes and has installed more than 400,000 m² of burlap, thus becoming a reference in Quebec with regards to the control of this species.

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Ania Wurster
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