There are four beaches that are unsafe for swimming this weekend.
The Windsor-Essex Health Unit has detected high levels of bacteria at Colchester Beach, Holiday Beach, Mettawas Beach and West Belle River Beach.
The health unit conducts beach water quality monitoring at ten public beaches every Wednesday from June to September.
Officials warn water quality can change from day to day and they do not recommend swimming if there was recent heavy rainfall, if the water is cloudy or if you are unable to see your feet in the water.