FLCA Receives Ontario Trillium Foundation Grant

Eurasian Watermilfoil – Dealing with the Threat

The FLCA was fortunate that in 2018, the Ontario Trillium Foundation, an agency of the government of Ontario, approved our application for a grant to help us with our efforts to control the spread of Eurasian Watermilfoil (EWM) in Farlain Lake for three years covering the period ending 2021!  Due to COVID restrictions and our inability to fully implement our management plan in both 2020 and 2021, the period was extended to the end of 2022.  Over the past five years, we have worked hard to develop strategies to control the infestation of this very aggressive aquatic plant based on extensive research, consultation, networking and experience. The grant will help provide us with the resources we need to purchase equipment, supplies and services needed to manage the EWM and protect the future of our lake.  It’s hoped that our learning and experience will also help other communities dealing with the EWM.

What is the Eurasian Water Milfoil (EWM)?

EWM is an extremely aggressive non-native invasive water plant that forms thick underwater stands of tangled stems and vast mats of vegetation on the water’s surface, especially in shallow lakes like Farlain Lake.  It was discovered in Farlain Lake in 2012 during a FLCA aquatic plant study of the lake. It had not been observed by Ontario government organizations studying water quality or the fisheries of the lake prior to that. The pioneer colony (original infestation) was limited to a small isolated area less than one acre in size on the southwest shoreline of the lake.

EWM is considered one of the most widely distributed aquatic invasive species with records of EWM confirmed in 47 continental USA states as well as the provinces of British Columbia, Ontario, and Quebec. Various organizations have been combatting EWM for years. For example, Lake George in New York State’s Adirondack Park has been managing EWM for 32 years. The Okanagan Basin Water Board in British Columbia has been combatting EWM for the past 40 years. Control budgets vary depending on the severity of the problem and the size of the water body. For example, the Christina Lake, British Columbia, EWM control program is $213,000 annually. To manage EWM and improve the lake’s water quality in Puslinch Lake Ontario, through dredging the annual operating cost is approximately $150,000.

EWM will grow from plant fragments created from physical breakage by boaters, anglers, and other disturbances (e.g. forceful wave action, aquatic animals, fish, waterfowl, etc.) during the summer months. In late fall during the end of its growth period EWM becomes brittle and naturally break apart. Plant fragments are the primary means of EWM reproduction; they float on the surface and are dispersed by wind and wave actions to other areas where they sink and colonize into new plants. In optimum water temperatures (15°C – 35°C) EWM plants can grow 30 cm per week.

Why is EWM a Problem?

EWM is an extremely aggressive invasive aquatic plant that forms thick underwater stands of tangled stems and dense floating mats of vegetation.Some of the problems associated with EWM include:

  • Recreational activities such as boating, fishing, and swimming are impeded by dense growth at or near the surface.

  • Shoreline property values can be de-valued. EWM choked bodies of water can depress real estate values up to 20%.

  • The lake’s ecosystem will be altered. EWM will displace important native plants thus harming fish and wildlife habitat. Dense floating vegetation becomes breeding habitat for mosquitoes.

  • Stagnant oxygen-depleted conditions are often found in association with dense beds of EWM. Sudden nutrient release caused by late-season die-back of extensive plant beds may cause nuisance algae blooms.

  • Costs to manage EWM growth are borne by either local citizens, lake management organizations, and/or local governments.

What is the FLCA Doing to Manage the EWM?

The FLCA implemented a EWM Control Program in 2014 under the leadership of the EWM Team working with the FLCA Board, and with the support of many volunteers from the community.  We also appreciate the ongoing support we receive from the Severn Sound Environmental Association (SSEA) and the Township of Tiny. 

Our current work on attempting to manage the Eurasian Watermilfoil is based on a series of steps starting with the development of the FLCA State of the Lake Report 2012 that then led to the LaketoSkyManagementPlanAug2013. As a result of these two documents that are due mostly to the efforts and authorship of one of our members and a past president, Peter Andrews. He discovered the EWM back in 2012 and since then has led the battle against the EWM. That included leading our EWM Steering Committee which consists of a very hard-working group of volunteers which was responsible for working with the FLCA Board on an EWM Integrated Management Plan which has formed the basis of our annual control efforts. That plan essentially includes three components: 1) application of the herbicide Reward, 2) installation of benthic mats in infested areas (bottom barriers), and 3) manual harvesting using DASH (Diver Assisted Harvesting). All of these components require authorization from various government agencies (Department of Fisheries and Oceans, Ministry of Natural Resources and Forestries, Ministry of the Environment, Conservation and Parks).

Each year we review the outcome of our efforts and develop a work plan for the following season based on the overall plan, modified based on our assessment. We’ve also worked hard on building our relationship with the local Township which has supported us in various ways, and with the SSEA – specifically its Invasive Species Coordinator, and in 2018 we were fortunate in obtaining a sizeable grant from the Ontario Trillium Foundation (OTF) to fund equipment, supplies, etc. for three years 2019-2021, now extended to the end of 2024 due to disruptions created by COVID and other issues.

Through ongoing research, we became aware of a new herbicide called ProcellaCOR which had been developed and used very successfully since 2018 in the US to eradicate the EWM in a number of lakes. Health Canada, through its Pesticide Management Regulatory Agency, PMRA, conducted a review of an application for the use of the herbicide in Canada starting in 2019 and granted registration finally in May of this year.

The Planning and Approval Process

Each year we review the sites, develop a report and draft management plan for the following year which must then be submitted to the Department of Fisheries and Oceans (DFO), and copied to the Ministry of Natural Resources and Forestries (MNRF) and the Ministry of the Environment, Conservation and Parks (MECP). That was completed this year by January 2023. Authorization to implement our management plan for the following year is required first from DFO, and then a permit for the application of a herbicide must be obtained from MECP.

We have now received approval to proceed with the application of the new herbicide ProcellaCOR to the infested areas on the lake this year and have received the required permit from the Ontario Ministry of the Environment, Conservation and Parks (MECP). Thhe application of ProcellaCOR is now planned for September 6, 2023. This is the culmination of over 6 months of ongoing, relentless communication with DFO and the MECP by our EWM Team.

About ProcellaCOR and the Treatment Application

ProcellaCOR is a new aquatic herbicide developed by SePRO, an environmental services company based in the US and now approved by Health Canada’s Pesticide Management Regulatory Agency (PMRA) as of May 2023. It has been used in over 200 lakes in the US and shown to be highly effective in removing EWM with no harmful impact on wildlife, fish, or humans.  Treatment of the EWM with ProcellaCOR this year was our preferred management strategy in the hope that we would have more success with this new product than our previous strategies as the plant has continued to spread in the lake.
Please refer to Dr. Mark Heilman’s presentation  in the AGM recording or ProcellaCOR Presentation MHeilman Aug 16 2023 for the PDF of his slides for details about ProcellaCOR. Dr. Heilman is a biologist with SePRO and responsible for the development of ProcellaCOR.  This herbicide is applied under water, not sprayed like Reward. It will be applied by SOLitude, a lake management company based in the United States, and currently the only one licensed to do so in Canada. Attached is a ProcellaCOR Q and A August 24 2023 document for downloading for further details about ProcellaCOR.
The following map shows the infestation sites which will be targeted for the treatment. Only these sites will be treated – the product will not be applied to the entire lake.


Shoreline property owners near the infestation sites were notified of the plans for treatment earlier this month and we have not received any major concerns.  The FLCA has used elerts, signage and Facebook to communicate plans to members.  Members of the community are welcome to send any comments, questions or concerns in to us at the FLCA general email box at inquiries@farlainlake.ca.
Buoys marking the sites to be treated have been placed on the lake. The markers will be removed following the treatment.  The EWM team reviewed all the sites and took images with our underwater drone to establish a baseline for the purpose of evaluating the effectiveness of the herbicide.

Advisory Recommendations for Lake Water Use Following Treatment

Swimming, wading, boating, fishing and domestic (household) uses are NOT restricted.  Use of water from the lake for IRRIGATION PURPOSES is subject to the following:
  • Do not use treated water for irrigation of greenhouse vegetables and fruits;
  • Do not use treated water for hydroponic irrigation without activated charcoal or similar filtration.
  • Do not use treated water for irrigation of residential gardens, turf grass, landscape vegetation or other non-food irrigation for 5 days after application.
  • Do not use treated water for irrigation of commercial field crops until concentrations are analytically below 2 ppb.

What to Expect Following Treatment

Post treatment, EWM plants will die-back over a 4 – 5 week period.
1 – 2 weeks after treatment:
EWM plants should still be standing but may look brown and wilted. The plant’s leaflets,which comprise the leaf, will fall off leaving a stem on branch. Branch stems curl and drop off.
2- 3 weeks after treatment:
Most of the plants (but not all) will have fallen to the bottom of the lake.  EWM biomass will appear blackened.
4- 5 weeks after treatment:
It will be difficult to detect any evidence of EWM plants.


We will be reviewing the impact of the treatment through the fall and Dr. Heilman is hoping to return to the lake to review  the effectiveness of the application.  Our agreement with SOLitude includes assisting with the evaluation and reporting of the treatment for a three year period, and provision for additional applications over the next two years if necessary.