Since 1918

The Gloucester Pool Cottager Association Members
Report on Eurasion Watermilfoil - an Invasive Species
October, 2012

We became aware of the extreme growth of Eurasion Watermilfoil (milfoil) this past spring and viewed the dramatic results during our water testing trip in the fall. Based on this, your board of directors sanctioned a survey of our lakes conducted by Kyle Borrowman, a biologist with Envirosciences Inc.. The purpose of the study was to:

  • Identify/verify the invasive plant
  • Record/map the areas with excessive growth
  • Identify possible remedial actions.


  • Gloucester Pool and Little Lake have infestations of milfoil that have been present for over 40 years.
  • Some areas have experienced excessive growth of the plant for the past 2 years. This has occurred in many parts of Ontario
  • The worst infestations are in Little Go Home Bay, Whites Bay, Lily Pad Bay and Burrows Bay.
  • MacLean Lake and Baxter Lake have very little milfoil.

The report and maps are available for viewing and downloading

Potential Remedies:

  • Envirosciences Inc. promotes a remedial action whereby the number of milfoil weevils is enhanced. This beetle occurs naturally in the environment and feeds on milfoil.
  • Harvesting. Cutting the weeds is a temporary solution. However, the cut weeds must be removed from the water. Failure to do so creates an even heavier infestation.
  • Chemical treatment has been successful in some circumstances
  • Water level control has been suggested. Apparently lowering water levels 2 – 3 feet, then raising them after freezing can help control this plant growth.

Note: None of these remedies have been sanctioned by Parks Canada for the Trent Severn Waterway.

What we have accomplished:

  • MPAC have a copy of the report. They can reduce property assessment in cases where weeds limit recreation possibilities. If you are in this situation, contact MPAC 866 296-MPAC (6722) or visit their website

Next Steps:

  • Your board intends to involve the municipalities, Ministry of Natural Resources and the Trent Severn Waterway in this problem. Our objective will be to identify mutually acceptable remedies.

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