Manitoba's busy Gimli Beach is under an E. coli advisory following a July 6 test.
An advisory has been posted to warn swimmers at the popular Lake Winnipeg beach.
The acceptable amount is 200 colony-forming units, or CFU, of E. coli per 100 millilitres; this week's test found 322 CFU.
To reduce the risk of illness, the province is advising swimmers to avoid swallowing water, wash hands after swimming and avoid swimming with an open wound or if you're sick.
If the water is high, or if there are strong north winds — conditions that may wash bacteria from the sand into the water — people are asked to reconsider taking a dip at all.
A test July 4 showed only 39 CFU per 100 millilitres, well within accepted guidelines.
Algae in southwest
Meanwhile, an algal bloom more than seven times the acceptable level has resulted in an advisory for Shoal Lake Beach.
On June 26, 783,000 blue-green algae cells per millilitre of water were recorded. The acceptable limit is 100,000 cells per millilitre.
Sandy Lake Beach south of Riding Mountain National Park also recorded huge algae blooms on June 28.
Heat, a lack of wind and sunny skies create optimum conditions for the growth of algae, according to the province.
People are advised to avoid swimming in both areas, as algae blooms can cause diarrhea and stomach cramps, or irritate eyes and skin. It's also important to avoid eating fish that look unhealthy from those waters.
As of July 8, the rest of Manitoba's beaches have been deemed safe for swimming. Updates are provided on the province's website.