Warning signs are posted around Belwood Lake advising people to take precautions because of the presence of blue-green algae.
The algae contain a toxin called microcystin that can cause illness when ingested by people or animals.
The signs were posted by Wellington-Dufferin-Guelph Public Health at several locations around the reservoir.
The Grand River Conservation Authority and public health are advising lake users:
– don’t swim in the lake;
– 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; and
– boating is allowed, but boaters should avoid contact with the water.
There have been no reports of human illness caused by the algae.
Park Superintendent Derek Strub said on Aug. 13 while the lake is currently no place to be swimming, the park’s separate swimming area in an old quarry is perfectly safe to use.
Belwood Lake is a 12 kilometre-long reservoir on the Grand River north of Fergus. At the south end of the lake is the Belwood Lake Conservation Area, a day-use park popular with boaters and picnickers. There is no designated swimming area in the park along the reservoir’s shore.
Around the rest of the reservoir are about 335 cottages on land owned by the GRCA, as well as several private campgrounds and day camps. Swimming is a common activity at these areas.
Signs are being posted at the park gatehouse and boat ramp, at a boat ramp in Belwood village, and at the private camp areas. Notices were also sent to cottagers and camp operators.
The algae bloom was noticed when mats of decaying algae started appearing on the shoreline. Samples were taken last week for analysis and 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.
Results of the tests were provided on Aug. 12, and the GRCA immediately issued the warning.
Although the algae on Belwood Lake are a blue-green variety, it has a purple colour because of the presence of harmless bacteria. Strub said there was no fish kill, which can often occur during an algae bloom.
The GRCA planned to re-sample the reservoir in a variety of locations this week to determine if microcystin is still present.
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. GRCA water quality staff believe that runoff from heavy rains in June may have carried additional phosphorous into the reservoir and that hot weather in July accelerated the growth of algae.
Blue-green algae blooms have also been reported in other parts of Ontario including Hamilton, Sudbury, and North Bay.
More information on blue-green algae is available in the Newsroom section of the GRCA website at www.grandriver.ca;
