Eurasian Watermilfoil

The PLA is implementing two important measures to defend the lake against EWM: on the July 1st, 2024 weekend, protective markers and signage will be installed (see the panel to the left for more details).  Later in the summer, a drone survey will be undertaken.  Read about it and how you can help here.

Eurasian watermilfoil is an aggressive invasive aquatic plant and is present in our lake.  See the locations in our lake with with reported sitings (enter Ompah, Ontario in the search bar).  Please take great care.  Fragments broken off by motor boats, fishing lures, or by pulling neighbouring weeds can root and cause the plant to spread. 

What can you do?

  1. You can try to control growth near your shoreline by carefully hand-pulling eurasian water milfoil plants, being careful not to cause any fragments to break off and to get the entire root.  (see below for how to identify this plant.)
  2. If you see floating fragments, carefully scoop them out of the water and dispose of them on land well away from the shore. 
  3. See the Ontario Invasive Plant Council’s  document on best management practices for Eurasian Water-Milfoil.
  4. Report a sighting.  Take a photograph, note the GPS coordinates, and email the information to  We will add the report to the distribution map for Ontario that is available here. 

Eurasian watermilfoil can out-compete native aquatic plants and eventually choke off portions of the lake.  Plants have been known to grow in water as deep as 10 metres. 

Not to be confused with the native Northern Watermilfoil, the easiest way to identify Eurasian Watermilfoil is by counting the pairs of leaflets on each leaf.  If there are more than 11 pairs, it’s Eurasian Watermilfoil.  It also becomes limp when out of the water unlike the native milfoil which remains rigid.  

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