Toronto Public Health is warning people to stay out of the water in some areas of west-end Toronto.
It has issued this warning to the public about the "concerning" blue-green algae blooms found in Humber Bay East.
The agency said it has received confirmation that the water samples taken from the mouth of Mimico Creek and in Humber Bay Park East tested positive for blue-green algae.
Toronto Public Health says it's easy to spot blue-green algae (also known as cyanobacteria). The plant-like organisms can range in colour from olive-green to red. They can form naturally in places such as ponds, rivers, lakes, and streams.
This toxic algae is harmful to people and can cause symptoms like headaches, fever, diarrhea and nausea.
If you come in contact with it, Toronto Public Health says you should wash as soon as possible with clean water.