Invasive Aquatic Species


Invasive alien species have no frontiers and that is why we find them on the territory of Val-des-Monts. The problem of exotic invaders is caused as much by the proliferation of wildlife species as exotic flora.

The zebra mussel

Water chestnut

Japanese knotweed

Eurasian Watermilfoil

Location of Watermilfoil areas observed between 2012 and 2015.

* This list is not exhaustive and needs to be revised and improved. 

The Federation is currently realizing a  rigorous follow-up on the detection and the mapping of Watermilfoil areas.

5 steps to protect your lake

Video prepared by the MDDELCC available at

Measures to prevent the proliferation of invasive species

It is important to minimize the effects caused by invasive species by limiting their proliferation. Collective efforts are important. Here are some tips to avoid and to limit the invasion of unwanted species on or near a body of water:

  • Find out about the origin of the species you are transplanting to your shorelines and gardens and choose native species.
  • Learn to identify invasive species in order to limit their proliferation. This will help eliminating them from your environment. You can also contact the Ministry of Sustainable Development, Environment and Climate Change to inform them of the location of this invasive species.
  • When leaving a body of water with your watercraft, remove plants and creatures that may be tied on to your boat or nautical equipment.     
  • When leaving a body of water ensure that the water from your motor boat has been drained.
  • Never bring water creatures or aquatic plants from one body of water to another.
  • Use a wash station, if there is one, before launching your watercraft in the water.
  • Wash the boat and equipment with hot water or a high pressure water jet and then allow it to dry for a minimum of 5 days.
  • Avoid composting invasive plants.



Eurasian milfoil is an invasive exotic species that has been present in many lakes in Quebec for many years. Originally from Eurasia, this aquatic plant propably found in our lakes through boats and other watercraft carrying fragments of milfoil. The great adaptability and rapid growth of this plant has allowed it to install in many environments. From small marshes, through ponds to large lakes, water milfoil has quickly invaded more than a hundred of our stream and is today at the origin of several environmental complications. 


Please consult the milfoil guide made by the MDDELCC. This describes the main characteristics of Eurasian Watermilfoil and those of similar species. 

His habitat 

Eurasian watermilfoil is an aquatic plant with great adaptability. It's not uncommon to find it in diverse habitats such as marshes, ponds, wetlands, rivers and lakes. Although he prefers temperatures above 15°C, he has the ability to survive freezing temperatures. Generally, the plants are fond along the banks at depths ranging from 1 to 4 meters. This aquatic plant prefers alkaline waters with a pH between 8 and 9 and like most plants they grow faster in nutrient -rich waters, espacially nitrogen.

dispersion mode  

The dispersion mode of the Eurasian watermilfoil is at the origin of the fast invasion encountered today. Indeed, it has a phenomenal dispersal capacity capable of increasing the population exponentially. The milfoil reproduce by cuttings, a reproduction mode which giving birth to a new individual identical to the mother plant with the aid of a single fragment of the latter. Although milfoil does cuttings on its own, human activities greatly favor this reproduction mode. A stroke of engine, paddle or even a kick is likely to fragment the milfoil plants and thus increase its density and distribution. This is why we don't recommend any type of activity in the areas where Eurasion watermilfoil is present to limit its dispersion. 

its impacts 

The invasion of a lake by Eurasian watermilfoil causes several environmenral and socio-economic problems. 

Environmental impacts 

  • Disturbance of the ecosystem 
  • Disruption of the local biodiversity by competing with native plants
  • Cause physicochemical changes in the lakes  
  • Promotes eutrophication by increasing the amount of organic matter in streams 
  • Create mosquito friendly habitats 

Socio-economic impacts 

  • Affect tourism and recreation activities 
  • Affect the value of the riparian properties 
  • Alters the landscape 
  • Loss of uses of the lake by the users 

Management and control tools 

1. Identification  

Before undertaking management and control measures, it must be ensured that there's Eurasian watermilfoil in the lakes. This is why it's important to learn how to identify invasive species with  an identification key and ask the advice of a professional.

2. Determine the distribution of herbaria 

The maping of the milfoil is very important to determinate the location of the colonies and their density. This step allows you to learn more about the extent of the problem and to set up an appropriate management plan. After the identification and location of the herbaria, it will be possible to install buoys to limit any activities in the infested areas. It's important to mention that early detection increases the chances of solving the problem. 

 3. Establishment of an intervention plan  

Several tools are now available to limit the spread of Eurasian Watermilfoil. It is important to mention that control methods are aimed at maintaining colonies at an acceptable level and not the complete eradication of the plant.

Watermilfoil control methods: updated knowledge

GOOd nautical practices to adopt to limit its spread 

Here is a short list of some simple practices to adopt on the lakes. 

  1. Lean to recognize the invasive milfoil to collect fragments floating on the surface of the water. 
  2. When you navigate on the lake and you see milfoil, turn off the boat engine if necessary and try to navigate where there's no milfoil. 
  3. When you see buoys indicating the presence of Eurasian Watermilfoil, pass out as much as possible of the buoys to avoid browsing the milfoil colonies. 
  4. Whenever you use a watercourse, inspect your boat and engine if applicable and clean them with a high-pressure water jet. If there's no cleaning station, take a cloth to remove debris from the boat. 
  5. Never transport plant species from one lake to another. 
  6. Never put milfoil in the compost. If you want to get rid of the fragments, dry them and burn them later. 
  7. Never try to emove milfoil by hand or with a rake. 
  8. Never transplant invasive plant species to riparian areas. 
  9. Avoid recreational activities such as fishing, swimming, kayaking and other activities in areas where there's a strong presence of milfoil.