Water testing this week has shown that levels of Escherichia coli (E. coli) were within recreational water quality guidelines at most beaches monitored by Manitoba Conservation and Water Stewardship.
On Lake Winnipeg, weather and lake level information appear to be good predictors of E. coli levels. Bacteria counts tend to increase when strong north 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.
E. coli counts were above the guideline at Gimli Beach on July 26. Exceedances of the guideline of 200 E. coli/100 ml were likely caused by the poor weather conditions that caused winds and waves to wash bacteria out of the sand and into the bathing water.
This week, algae blooms were reported on Lake Winnipeg at Victoria and West Grand beaches, at Big Whiteshell Lake beach and at Killarney Lake beach. The number of blue-green algae cells and the concentration of the algal toxin microcystin were below the recreational water quality guideline at all four locations.
Algae blooms were also reported on Pelican Lake at Ninette and at Pleasant Valley. The number of blue-green algae cells was above the recreational water quality guideline on July 23 at Pelican Lake at Ninette and at Pleasant Valley. The concentration of the algal toxin microcystin was below the recreational water quality guideline at both locations.
Algae advisory signs are posted at Pelican Lake (Pleasant Valley and Ninette) and on Lake Winnipeg at Hillside Beach, West Grand Beach and at the lagoon at West Grand Beach.
Algae blooms are difficult to predict and may form and then disperse quickly, or last for several days or weeks. Warm and calm weather coupled with relatively high nutrient loads provide ideal conditions for blue-green algae to develop.
People are reminded to avoid swimming in water where severe algae blooms are visible and to prevent pets from drinking water along the shoreline.