Warning signs are being posted at Conestogo Lake reservoir advising people to take precautions because of the presence of blue-green algae. The algae contains a toxin called microcystin which can cause illness when ingested by people or animals.
The signs are being posted at the Conestogo Lake park gatehouse and beach. Cottagers surrounding the lake are also being notified of the advisory.
The Grand River Conservation Authority and Wellington-Dufferin-Guelph public health are advising reservoir users:
– Don’t swim in the reservoir
– Keep children and pets away from the algae
– Avoid contact with the algae
– Don’t eat fish from the lake
– Don’t use the water for drinking or any other purpose
– Boating is allowed, but boaters should avoid touching the algae.
There have been no reports of human illness caused by the algae.
Conestogo Lake is a 735 ha reservoir on the Conestogo River. It was completed in 1958 for flood protection and to provide water to maintain flows downstream during dry weather.
The reservoir is very active with numerous water Sports and activities. There is a beach located within Conestogo Lake Park and many cottages surround the reservoir.
The algae bloom was first noticed when mats of decaying algae started appearing on the shoreline. Samples were taken on Monday for analysis which showed that the algae contained the toxin microcystin. When the algae die, the toxin is released in the water where it naturally breaks down in about five to seven days.
Algae blooms are a natural phenomenon. They tend to occur during hot, dry weather. Algae feed on phosphorous, a chemical found naturally in soil as well as in manure, fertilizers and human waste.
An algae bloom at Belwood Lake reservoir near Fergus in August led to restrictions on water activities there. Those restrictions have since been lifted.
More information on blue-green algae is available:
– in the Newsroom section of the GRCA website at www.grandriver.ca
-on the Health Canada website at: http://www.hc-sc.gc.ca/ewh-semt/alt_formats/pdf/pubs/water-eau/guide_water-2012-guide_eau/guide_water-2012-guide_eau-eng.pdf and on the Ontario Ministry of Environment website at https://www.ontario.ca/page/blue-green-algae
