One of two beaches on Little Lake in Peterborough, Ont., was ordered closed on Wednesday following the discovery of suspected blue-green algae blooms.

Peterborough Public Health’s water testing by staff on Wednesday reported possible blooms at Rogers Cove beach on Maria Street.

Nearby Beavermead Park beach on Little Lake was also declared “unsafe” on Wednesday, indicating higher-than-normal levels of bacteria.

The health unit says unsafe levels of bacteria may be due to heavy rainfall, large numbers of waterfowl or swimmers or high winds or wave activity.

The Peterborough area had heavy rain on Tuesday night into Wednesday as remnants of Hurricane Beryl in the U.S. arrived.

“Although a beach may be open or posted as safe, we recommend avoiding swimming for at least 48 hours after recent heavy rainfall or if you cannot see your feet when standing in the water,” the health unit stated.

Of the beaches in Peterborough County tested weekly, one was deemed unsafe on Wednesday: The Squirrel Creek Conservation Area on Wallace Point Road in Otonabee-South Monaghan Township.

The health unit also conducts monthly tests at Belmont Lake Beach in Belmont, Chandos Beach in North Kawartha, Quarry Bay in Woodview, White’s Beach and Trent Lakes and Kasshabog Lake in Havelock. The most recent results between June 24 to July 3 reported all the beaches as safe.

In July 2023, Rogers Cove was closed for an extended period due to blue-green algae blooms which the health unit warns can cause eye irritation, skin rashes and itchy skin. It’s also dangerous for pets such as dogs.