Eurasian Milfoil
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Letter from Tim Hannah, Ministry of Environment: Feb. 13, 2024

Hello Vern,

Thank you for your call today.  In order for your lake management group to control the Eurasian milfoil with an aquatic herbicide, you will need to hire an exterminator possessing an Aquatic Vegetation Licence.  You will also require a permit issued by the Ministry of the Environment, Conservation and Parks (MECP).  An Application for a Permit to Perform a Water Extermination would be required to be submitted to the Regional Pesticide Specialist where the extermination is proposed to take place, as your lake is in Eastern Region, that would be me.  The application form itself can be found at this link:  Application for a Permit to Perform a Water Extermination - Forms - Central Forms Repository (CFR) (  


Attached you will find the Aquatic Herbicide Guide for 2023 (in draft still) which will provide detailed information on applying for a Permit, and outline all steps and information required to be submitted with the application form.  The exterminator you hire will fill out the application, and submit the required information.


Besides requiring a Pesticide Permit issued by our Ministry, you must to comply with any other applicable legal requirements, including the prohibition on depositing a deleterious substance in water frequented by fish or in any place that may result in the substance entering any such water, contrary to subsection 36(3) or any other provision of the federal Fisheries Act.  As Environment and Climate Change Canada and/or Fisheries and Oceans Canada administer the Fisheries Act, you should contact them for any information about or interpretations of the Act. The contact for Environment and Climate Change Canada is  Information on Fisheries and Oceans Canada requirements, including a form to request a review of a near water project is available at


An approval may be required from Fisheries and Oceans Canada under the Aquatic Invasive Species Regulation under the Fisheries Act which would enable you to control the weeds, if they are an invasive species.  It is most likely Fisheries and Oceans Canada would deny approval to undertake any extermination if the plants are not aquatic invasive species, but that is their decision to make.  


A Letter of Advice may also be required from the Fisheries and Oceans Canada, Fish and Fish Habitat Program, if there are Species at Risk identified in the waterbody where you will be undertaking this treatment. Contact information for these issues is found in the guide document attached.  (you can also look up your lake in the following website to find Species at Risk: Aquatic species at risk map (


Please let me know if you have further questions.






Tim Hannah, B.Sc., C.Dir.
Pesticides Specialist (A)

Technical Support Section, Eastern Region

Ministry of the Environment, Conservation and Parks