The beach and swimming area at Christie Lake Conservation Area has been closed to swimmers and animals, the Hamilton Conservation Authority said in a news release on Friday.
Water samples taken from several spots along the shoreline showed the presence of blue-green algae, confirmed Hamilton Public Health Services.
The naturally occurring algae, known as cyanobacteria, can produce toxins known as microcystins, which are a health risk to humans and animals. It typically forms in shallow, warm and stagnant or slow moving water.
Skin contact with or accidental ingestion of the algae can lead to a number of symptoms including a rash or other skin irritation, red eyes, swollen lips, sore throat, fever, nausea, vomiting and diarrhea.
The Hamilton Conservation Authority says the most serious of these are caused by drinking the contaminated water.
A timeline for reopening has not been provided at this time.
