Toronto Public Health is advising people to stay out of - and refrain from drinking - the water at Humber Bay Park East and at the mouth of Mimico Creek, due to the presence of blue-green algae.
Also called cyanobacteria, the Ministry of the Environment says recent water samples confirmed it is currently living within these bodies of water. The algae can potentially produce toxins that make us ill.
The algae appears in colours ranging from olive green to red. When fresh, it smells like freshly cut green grass, but once it starts to decay, its smell has been compared to rotting garbage.
Toronto Public Health says exposure to these potential toxins can result in a wide range of flu-like symptoms, including headaches, fever, diarrhoea, stomach pain or nausea and vomiting. It can also cause skin rashes and irritate mucous membranes.
But this isn't just a risk to humans. Dogs and other pets should also be kept away from the water as it can make them sick as well.
If you do find yourself in contact with the water in these areas, officials recommend washing yourself, children and pets with clean water as soon as possible. You should also contact your doctor if you experience any symptoms as a result of exposure to the water.
There's no timeline as to when the bacteria may subside. Toronto Public Health says beaches in the Humber Bay Park East area are not regularly monitored for water quality.