The toxins in the algae can irritate the skin and, if swallowed, cause diarrhea and vomiting.

"Residents of Whitestone Lake 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," said the health unit. "Due to the many factors involved, government authorities are unable to determine where and when there are no toxins."