The North Bay Parry Sound District Health Unit says that a harmful algal bloom (cyanobacteria), also known as blue-green algae, has been found in Lake Nosbonsing. Species of the algae capable of producing toxins were confirmed by the laboratory of the Ministry of the Environment, Conservation and Parks. The toxins in harmful algae can irritate the skin and, if swallowed, cause diarrhea and vomiting. Residents of Lake Nosbonsing may be affected depending on their closeness to the algae bloom, the size of the lake, wind direction, water flow, and other environmental conditions that cannot be predicted or controlled. Due to the many factors involved, government authorities are unable to determine where and when there are no toxins. Users are advised to exercise their judgment before using the water.