People are being warned to stay out of water that may have a shimmering, foamy pea soup appearance.
The Saskatchewan Water Security Agency and health officials said blue-green algae blooms occur in waters with the above description.
Algae blooms typically occur during calm, hot weather in lakes and reservoirs with shallow, slow moving, or still water that have sufficient nutrients.
They are usually blue-green, bright blue, grey or tan in colour and can last up to three weeks.
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Officials said people should not swim in or drink water where blooms occur.
Doing so could cause red skin, sore throats, cramps or diarrhea.
Caution should also be exercised when consuming fish or shellfish caught in or near blooms.