The Simcoe Muskoka District Health Unit has issued swimming advisories for beaches in Midland and Tiny Township.
Pete Pettersen Park Beach in Midland, as well as Jackson Park and Woodland Beach in Tiny Township are both affected.
A swimming advisory is issued when the bacteria levels exceed those considered acceptable by the health unit. When an advisory is in place, warning signs are posted around the beach indicating there may be an increased risk of developing minor irritations and infections if you swim.
If people choose to swim during an advisory, they should avoid dunking their heads or swallowing the water, according to the health unit.
Bacteria counts can vary depending on the conditions, with the most common culprits being rain, wind and water fowl.