1. What is Eurasian watermilfoil?

Eurasian watermilfoil is an invasive aquatic plant originating in Europe and Asia. It arrived in North America during the 1950s and since then has continued to spread. It forms dense plant beds at depths ranging one to 10 metres.

Eurasian watermilfoil has no natural predators to curb its proliferation. As well, the plant has another advantage to speed its reproduction: one small part of a stem can take root to create a new plant. Plant fragments can be transported from one lake to another by boats, trailers, fishing gear and other nautical equipment.

To better understand and be able to identify Eurasian watermilfoil, consult the Canadian Invasive Species Centre
https://invasivespeciescentre.ca/invasive-species/meet-the-species/invasive-aquatic-plants/eurasian-water-milfoil/

2. Problems caused by Eurasian watermilfoil

Experts agree that Eurasian watermilfoil is threatening the environment of our lakes. They recommend taking action against this plant not only because of its invasive character but also because it disturbs natural ecosystems and disrupts local biodiversity. It negatively impacts the reproduction of some fish and of indigenous aquatic plants. If it is allowed to spread freely, it can negatively impact activities like swimming and fishing. As well, its spread can lower lake property values, as seen in other regions in Quebec where Eurasian watermilfoil has spread uncontrolled. We know that, once established, it is very difficult to remove.

3. Situation on our two lakes

Every year, the APLC carries out inventories in the Cedar lakes to identify Eurasian watermilfoil weedbeds. Since 2015, watermilfoil has been spotted in Petit lac des Cèdres while, to date, the APLC has not yet detected its presence in Grand lac des Cèdres.

The results of the 2018 and 2019 inventories, which had been carried out by a team of volunteers supported by the ministry of forests, revealed that, in Petit lac des Cèdres, Eurasian watermilfoil covered a total area of ​​approximately 14,000 m². On the other hand, the 2022 inventory, completed by the firm Fyto, shows that the total area is estimated at 39,000m² of weedbed with a density of 25% and more of invasive plants.

In 2023, a fall survey showed that the area of weedbeds containing more than 25% Eurasian watermilfoil had dropped by over 50%. But in 2024, the invasive plant made a strong comeback—its presence doubled, covering about 30,000 m² of weedbeds with more than 25% density.

Summary of areas to treat in Petit lac des Cèdres

Type of weedbeds: A monospecific weedbed has a component of Eurasian watermilfoil in excess of 80%. The ministry allows the installation of tarps on these weedbeds only. For any other weedbed made up of native plants and less than 80% Eurasian watermilfoil, the ministry specifies the technique of uprooting.

 Note: These estimates are made in the fall and reflect the impact of that year’s treatment.

 4. Summary of the intervention strategies

The project to fight against Eurasian watermilfoil brings together several strategies aimed at curbing its growth in Petit lac des Cèdres and preventing its entry into Grand lac des Cèdres.

Click to see 2023 financial plan   (French only)

Strategy 1 – The laying of reusable synthetic tarpaulins:

The technique consists of unrolling a tarpaulin on the entire weedbed and anchoring the tarp on the bottom of the lake with metal rods. The tarp prevents the growth of the plants while allowing the free flow of gasses through the tarp so that it remains wedged at the bottom of the lake.

The use of reusable tarps allows for rotation between weedbeds from year to year. The tarps are installed at the beginning of the season, removed after eight to 10 weeks, then cleaned, and stored. The following year, divers do a check to make sure that the watermilfoil does not return to the treated weedbed, and they uproot any stems that may have survived. A synthetic tarp has a lifespan of eight to10 years. 

Strategy 2 – Removal of roots: 

One method, with encouraging results recently in the United States and Canada, is the removal of the plant and its roots by experienced divers. There is a protocol for this developed by the Réseau de surveillance volontaire des lacs (RSVL). This technique will only be used for weedbeds where watermilfoil is intermingled with native plants (mixed beds), where the use of tarps is prohibited by government. 

Strategy 3 – Installation of buoys: 

At the same time, yellow buoys are installed every spring for the summer season to mark the Eurasian watermilfoil sites in Petit lac des Cèdres. The objective is to make these sites easily identifiable so that people avoid entering the areas with their boats, fragmenting the plants and transporting pieces elsewhere, thus accelerating further growth.

Strategy 4 – Inventory and identification service for residents:

Surveys of the plant are carried out each year at the end of summer, following the method recommended by the Réseau de surveillance volontaire des lacs (RSVL) of Québec’s ministère de l’Environnement et de la Lutte contre les changements climatiques (MELCC). The APLC offers an identification service to all residents who think they’ve spotted the plant in areas of the lake outside the known zones.

Strategy 5 – Information and awareness campaign: 

This campaign will provide information on problems resulting from invasive species, using several communication methods aimed at informing residents:

• Reminder of the importance of boat washing before launching (in partnership with the Municipality of Messines)
• Warning to avoid zones marked by yellow buoys
• Awareness meetings for owners who have properties near Eurasian watermilfoil
• Reminder to avoid areas marked by buoys to prevent disturbing or damaging the tarps installed on the lake bottom

5. Activities

2025 - Planned activities for the current year

• Contract was renewed for a fourth year with Fyto, a company that specializes in managing invasive species. They will carry out the following activities:
  • Installation of tarps (6,500 m²)
  • Manual uprooting (focus on areas adjacent to newly installed tarps and previously treated areas)
  • Removal of tarps placed on shallow areas in the northern part of Petit lac des Cèdres
  • Survey of Petit lac des Cèdres by the Fyto team (planned for the fall)
  • Survey of the stream between the two lakes and the entrance to Grand lac des Cèdres (also planned for fall)
  • Preparation of an activity report
• Buoy placement and signage on affected weed beds
• Funding request submitted to the Municipality of Messines, along with efforts to secure additional sources of funding

2024

• 2024 activity report was received from Fyto, including the surveys conducted at Petit lac des Cèdres and Grand lac des Cèdres.
• Contract was renewed for a third year with Fyto, a company specializing in the management of invasive exotic species.
• More than 100 tarps were installed on 16 dense watermilfoil beds (with density exceeding 80%), covering approximately 6,473 m². In addition, manual uprooting was completed over 36 days, removing nearly 12 tonnes of watermilfoil from an area of about 32,792 m².
• Refined practices: Using more opaque tarps and installing them earlier in the season has increased the effectiveness of this method. No watermilfoil was found on treated areas after these opaque tarps were removed, and similar results were observed across all treated weedbeds.
• Treatment of the two shallow areas at the north end of Petit lac des Cèdres: Tarps were installed in spring 2023 but were not removed in the fall due to regrowth of watermilfoil underneath. Over the summer of 2024, Fyto monitored the situation and decided to keep the tarps in place for a second year. They are set to be removed in spring 2025.
• Buoys were installed to mark watermilfoil beds covered by tarps. Several fishing hooks were found on the tarps, causing damage and shifting some of them. As a result, watermilfoil could not be effectively removed where the tarps had been moved.
• No watermilfoil beds were found in Grand Lac des Cèdres.
• Individual watermilfoil plants were still detected this year in the creek connecting Petit Lac des Cèdres to Grand Lac des Cèdres, despite efforts to remove plants from the same location the previous year.
• The APLC signed a $172,000 agreement with the Fondation de la faune du Québec to support ongoing efforts to manage Eurasian watermilfoil in Petit Lac des Cèdres and protect lake trout habitat.
• Requested and secured $10,500 in financial assistance from the Municipality of Messines.
• Launched a community fundraising campaign. We collected nearly $6,500.
• Conducted an awareness campaign about invasive species and the importance of washing boats, targeting residents and visitors to our lakes.

2023

• 2023 activity report was received from Fyto, including the surveys conducted at Petit lac des Cèdres and Grand lac des Cèdres.
• Installed buoys to mark the location of tarps covering weedbeds of Eurasian watermilfoil.
• Submitted a new request for financial assistance to the Fédération de la Faune du Québec (FFQ) to continue our efforts to control the Eurasian watermilfoil infestation. In early 2024, the FFQ granted the Association $172,000 for this effort.
• Requested $10,500 in financial assistance from the Municipality of Messines.
• Raised a little more than $8,000 through a community fundraising campaign.
• Signed a second-year contract with Fyto, a company specializing in the management of invasive exotic species. Fyto installed 6,500 m² of tarps over weedbeds in shallow areas in the northern part of Petit lac des Cèdres, and carried out manual uprooting treatments over 10,000 m².
• Fyto also included in the survey an analysis of weedbeds with zero to 25% watermilfoil, to better understand the plant’s progression in Petit lac des Cèdres. This portion of the inventory confirms that these weedbeds cover about 58,000 m².
• Conducted a survey of Petit lac des Cèdres, where we discovered two previously unknown weedbeds. The inventory found 18,500 m² of weedbeds with a density of more than 25% Eurasian watermilfoil in the lake and approximately 55,000 m² of weedbeds with a density less than 25%.
• Conducted an inventory of Grand lac des Cèdres, finding no Eurasian watermilfoil except for a few stems in the stream, which were removed.

2022

• Full 2022 activity report was received from Fyto, including the survey results for Petit lac des Cèdres and Grand lac des Cèdres.
• Buoys were placed marking the Eurasian watermilfoil beds.
• We made a submission to the Fondation de la faune du Québec’s Invasive Exotic Plant Control Program, resulting in a $64,900 grant awarded for the project.
• A grant of $8,500 was provided by the Municipality of Messines.
• In a fundraising campaign with residents, the APLC collected $11,295.25, which is in addition to the $20,276 collected in 2021.
• Tarps were installed by Fyto divers on weedbeds 3, 4, 5, 8, 9, 10, 12, 18, for a total area of ​​4,085 m².
• Uprooting of Eurasian watermilfoil on multiple weedbeds was done by Fyto divers. In total, 1,313 kg of fresh biomass were uprooted from an area approximately 3,000 m². 
• Tarps were removed in August 2022.
• A survey of the Cedar lakes was done at the end of the summer by the Fyto team. The estimated area with over 25% watermilfoil cover was adjusted from 16,000 to 32,000 m²—a 100% increase.
• The FINANCIAL PLAN  (French only) for the project was updated.

2021

• Placement of buoys marking the Eurasian watermilfoil beds
• Request for permit for the placement of tarps
• Initial purchase of 1,500 square metres of reusable synthetic tarps
• Assembly of 50 rolls of tarp, and the construction of a motorized barge with a pulley and reinforcing metal bars to handle the unrolling of the tarps.
• Laying of the tarps on June 8 and 9, 2021, with three divers and a dozen volunteers to validate our methodology.
• Treatment of two weedbeds upstream on the lake, in line with the strategic action plan developed in cooperation with the provincial government.
• Removal of synthetic tarps on August 16th and 17th. After a visual inspection of the two target weedbeds, it seems that all the stems of watermilfoil are dead.
• Survey of the Cedar lakes at the end of the summer by trained volunteers from the APLC and an employee of the MFFP
• No uprooting activity scheduled this year due to COVID-19

2020

• Placement of buoys to mark Eurasian watermilfoil areas
• Installation of movable sandwich boards to inform residents of the placement of the yellow buoys
• Removal of Eurasian watermilfoil roots (activity delayed until 2021 due to COVID-19)
• Inventory, at the end of the summer, of both lakes by volunteers trained by APLC
• Consultation and training with experts from Université Laval on tarp deployment techniques and other logistical considerations

2019

• Placing buoys to identify Eurasian watermilfoil areas
• First root pulling activity in June with experienced divers and APLC volunteers.
• Meeting with residents who live near Eurasian watermilfoil plants to encourage them to avoid boating there
• Distribution of a flyer to inform residents of the presence of Eurasian watermilfoil and the reason for the yellow buoys
• Inventory of both lakes by APLC volunteers—two new plant areas spotted in Petit lac des Cèdres—a total of seven. No Eurasian watermilfoil plants found in Grand lac des Cèdres (section outside Kitigan Zibi reserve)
• Participation in a conference offered by the Lac des Plages association, innovator of the root removal technique
• Publication of an educational resource on the APLC website, explaining problems linked to exotic invasive species
• Installation of movable sandwich boards to inform residents of the placement of yellow buoys
• Information session about the pilot project at the APLC annual meeting

2018

• Inventory of the two lakes by APLC volunteers—two new plants were seen in Petit lac des Cèdres, for a total of seven plants. No plants were found in Grand lac des Cèdres outside Kitigan Zibi reserve)
• Participation of APLC board members at a Eurasian watermilfoil conference offered by l’Université Laval à Québec
• Information workshop on invasive species for residents
• Approval by the APLC board of a pilot project to fight Eurasian watermilfoil
• Negotiation to obtain permission from the Municipality of Messines for root removal
• Installation at the boat launches of a sign informing visitors of the requirement to wash boats before launching
• Full 2022 activity report was received from Fyto, including the survey results for Petit lac des Cèdres and Grand lac des Cèdres.
• Buoys were placed marking the Eurasian watermilfoil beds.
• We made a submission to the Fondation de la faune du Québec’s Invasive Exotic Plant Control Program, resulting in a $64,900 grant awarded for the project.
• A grant of $8,500 was provided by the Municipality of Messines.
• In a fundraising campaign with residents, the APLC collected $11,295.25, which is in addition to the $20,276 collected in 2021.
• Tarps were installed by Fyto divers on weedbeds 3, 4, 5, 8, 9, 10, 12, 18, for a total area of ​​4,085 m².
• Uprooting of Eurasian watermilfoil on multiple weedbeds was done by Fyto divers. In total, 1,313 kg of fresh biomass were uprooted from an area approximately 3,000 m². 
• Tarps were removed in August 2022.
• A survey of the Cedar lakes was done at the end of the summer by the Fyto team. The estimated area with over 25% watermilfoil cover was adjusted from 16,000 to 32,000 m²—a 100% increase.
• The FINANCIAL PLAN  (French only) for the project was updated.

2015

• First inventory of Eurasian watermilfoil in Grand lac des Cèdres and Petit lac des Cèdres by ABV des 7
• ABV des 7 report