Manitoba Water Stewardship advises that testing has shown that levels of Escherichia coli (E. coli) were within recreational water quality guidelines at most beaches monitored this week by the department. Each summer, about 60 beaches are routinely monitored in Manitoba.
Escherichia coli counts were above the guideline at Victoria, Albert, East Grand, Sunset, Patricia, Gimli, and Hnausa beaches on Lake Winnipeg on June 22, but quickly returned to within guidelines by June 24. Exceedance of the guideline of 200 E. coli per 100 mL was likely caused by weather conditions when winds and waves led to bacteria being washed out of beach sand and into the water.
On Lake Winnipeg, weather and lake level information appear to be good predictors of E. coli levels. Bacteria counts tend to increase when strong northerly winds cause water levels to temporarily increase and large waves wash bacteria out of beach sand. When calmer weather returns, E. coli bacteria levels typically fall quickly to below guideline levels.
Blue-green algae have not been reported from Manitoba beaches. The formation of algae blooms is difficult to predict. Warm and calm weather coupled with relatively high nutrient loads presents ideal conditions for their development. Algae blooms often appear in Manitoba Lakes during July and can last until mid-September. Since algae blooms can reoccur during period of warm and calm weather, bathers are reminded to avoid swimming in water where severe algae blooms are visible.
