By Joanne Burghardt, SLCA president May 2025
The Steenburg Lake Community Association (SLCA) continues to research how to control and remove Eurasian Water-Milfoil (EWM). In this article we look at recent control and removal projects around Steenburg Lake and elsewhere in Ontario.
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Three years ago, a staff report for a Crowe Valley Conservation Area (CRVA) board meeting described the spreading problem of Eurasian Water-Milfoil (EWM) in area lakes.
“An invasive species, the aquatic plant Eurasian Water-Milfoil, is beginning to establish itself in lakes and create problems for residents and cottagers in the Crowe Valley watershed.” – Crowe Valley Conservation Authority (CRVA), April 21, 2022, Agenda item
EWM is an invasive perennial which, once established, can form dense underwater mats of vegetation that can negatively impact the ecosystem of a waterbody, including displacing native plant species, altering food-web structures, reducing macroinvertebrate abundance and diversity, and degrading the quality of fish habitat.
These thick mats also reduce the aesthetic appeal of a water body, decrease property values and impact recreational activities such as swimming and boating, and can clog industrial and power generation water intakes.
At their April 2022 Board meeting, the CRVA reviewed a request from Twin Sisters Lakes Ratepayers Association (TWLRA) asking for the CRVA’s support of the use of herbicides to control EWM in the lake. The request was denied citing the negative side effects herbicides can have on the lake ecosystem.
At the time, the CRVA suggested Twin Sisters-Lakes “implement nonchemical solutions similar to those implemented in the Chandos Lake Eurasian Watermilfoil Management Plan prior to moving forward with the application of potentially dangerous pesticides, since the control measures of removal, placing of benthic mats seeded with native plants, and the use of biocontrol all have a much lower impact on the health and wellbeing of other animal and plant species in the ecosystem and do not impact water quality”.
Attempts to reach TWLRA for an update on their situation were unsuccessful.
The Chandos Lake Property Owners Association (CLPOA) initiated their Eurasian Water-Milfoil Management Project in 2018, in association with Trent University. The research project focused on managing EWM with two pillars: use of benthic mats seeded with vegetation, and the release of milfoil weevils (a biological intervention).
The mats were made of biodegradable materials, such as coconut husk. They were laid on the lake bottom after EWM was removed. To further accelerate restoration of the site, native aquatic plants were seeded in the mat.
The SLCA reached out to the CLPOA and was advised the seeded mats had been expensive and labour intensive.
They report some success using floating tarps in the spring to cover large areas of the lake infested with EWM. Large tarps supported by pool noodles are floated over large patches of EWM early in the spring and anchored in place. They stop the sun penetrating the water and the EWM doesn’t grow,
The success of using milfoil weevils to naturally attack the EWM was unclear.
Chandos now focuses their invasive species control on educating their property owners on identification and stopping the spread. A source of concern, says their spokesperson, are their public boat launches where Clean, Drain, Dry protocols are not followed, and invasive species can enter the lake.
Read more about the Chandos project: https://clpoa.ca/our-lake/love-chandos-lake/eurasian-watermilfoil-management-project/
Wollaston Lake Home and Cottage Association (Coe Hill) Began looking at EWM following a lake survey done in 2017 by FOCA (same time Steenburg had ours done). They began with education. Every year they hold an education event, usually at their association BBQ.
By 2021 the executive couldn’t keep up with it so they formed an EWM Action Committee to take over and that year started installing yellow floating markers to mark their EWM beds and get boats to avoid driving through them. Similar to the rock markers on Steenburg, Wollaston installs the yellow buoys each spring. In 2025 they are up to 60 markers (about 4-8/bed).
One of their members is a local councillor who pushed for harvesting to open up channels through the milfoil for boat traffic. They harvest an area 3mx40m every year, by fall it grows back.
They continue to use biodegradable coconut shell benthic mats, installing up to 10 per year in a partnership with a Belleville dive club. The mats degrade over 5 years, no plastics. They have a standing permit to treat 25,000 metres of lake area and use that same permit year after year as long as they don’t change the treatment area.
In 2024 and in 2025 they received grants from the Invasive Species Action Fund (Invasive Species Centre/OMNR): $1,000 for the installation of benthic mats to reduce the prevalence and spread of Eurasian Water-Milfoil; $1,000 for the installation of Transport Canada approved floating signs on marked beds and for boating channel creation via mechanical harvesting of Eurasian Water-Milfoil In 2021 they received a $1,000 grant to manage the infestation of Eurasian Milfoil in Wollaston Lake through broad community engagement and education. This is in addition to grants from the municipality and in-kind donations of benthic mats.
In 2025 they are polling property owners (about 250 in total) to gauge interest in using the chemical ProcellaCOR FX to kill EWM. Est. cost $34,000 each of yr 1, 2 and 4 to kill it.
They used a reverse contour map of the lake to calculate where milfoil might spread to based on water depth to help educate their members.
Picard Lake Cottage Association (Peterborough) (2025) received a $1,000 grant to test two different methods of EWM mitigation for their effectiveness – floating tarps and underwater manual removal.
Actions being taken by lake associations in Limerick Township in 2025:
