Two Lake Huron beaches have been deemed as unsafe for swimming this long weekend.
Lambton Public Health said warning signs are up at Brights Grove Beach, including Mike Weir Park, and Grand Bend South Beach.
The health unit also conducts regular sampling at Pinery, Ipperwash, Highland Glen, and Canatara Park.
Residents are reminded that following heavy rainfall, the water at area beaches may be temporarily polluted for up to 48 hours.
Lambton Public Health does not conduct water sampling along the St. Clair River.