Eurasian Watermilfoil Management Project

Photo: Trent University

What is the Eurasian Watermilfoil Management Project?


In response to residents and environmental representatives, the CLPOA initiated an Aquatic Invasive Species (AIS) management project in 2018 in association with Trent University. The research project focuses on managing the invasive aquatic plant Eurasian watermilfoil (Myriophyllum spicatum) invading Chandos Lake. The management project is completed in an integrated approach, with two principle pillars:


  1. Placement of benthic mats seeded with vegetation. The mats are made of biodegradable materials, such as coconut husk. They are laid on the lake bottom after Eurasian watermilfoil is removed. They act much like a shade cloth does in a garden, and prevent milfoil from growing after treatment. To further accelerate restoration of the site, native aquatic plants are seeded in the mat.
  2. Release of milfoil weevils (Euhrychiopsis lecontei) a small aquatic insect. This native insect is used as a form of biocontrol and feeds on the Eurasian watermilfoil over the summer.


What are the phases of the project?


Phase 1 (summer of 2018) – Five control and five treatment sites were selected around the lake where active management took place. Control sites were also set up to monitor changes without active intervention. Each treatment site received one benthic mat (2m by 8m in size) and a portion of the 25,000 total weevils released.


Phase 2 (summer of 2019) – Expanded research project by installing an additional 80 benthic mats. Of these 75 were new locations, that have been coordinated with participating cottagers and approved by the Ministry of Natural Resources and Forestry. The remaining 5 mats were used to revamp treatment sites from 2018. The mats are the same dimensions and materials used in the previous year with desirable native aquatic plants seeded in the mats.


Phase 3 (summer of 2020) – Continue to install benthic mats in areas with significant milfoil. Explore other management options, such as the raising and releasing of aquatic milfoil weevils to feed on the milfoil. Monitor previous treatment sites for long term changes. Possibly use drone mapping of shoreline to identify the extent of the Eurasian watermilfoil population. Drone imagery can later be used to reveal the success of other management practices.


Any questions? Or to sign up for a mat. Contact Alex Haney, CLPOA Love Chandos Lake Director at


Project Publications