The beach at Tuscarora State Park in Barnesville remains closed to swimming because of harmful algae.

The Pennsylvania Department of Conservation and Natural Resources closed the beach on Friday after water tests detected harmful algae.

The beach will remain closed until acceptable water sample results are received. DCNR has posted signs at the beach and all major access points. This is the third time this season that the lake has been closed because of the algae.

DCNR said that harmful algal blooms occur when certain kinds of microscopic organisms in a water body produce toxins or other chemical compounds in concentrations that can harm people, pets or other animals. The microscopic organisms that most commonly bloom in Pennsylvania are cyanobacteria, or blue-green algae. Cyanobacteria are a natural part of many aquatic ecosystems, but some types produce cyanotoxins that can be harmful in high concentrations.

Caution should be taken when doing activities on or near the lake. Pets should be kept out of the water and kept from drinking any water from the lake. Visitors should not boat or paddleboard in water with scum or discoloration.

Other activities at Tuscarora State Park, such as camping, picnicking and hiking are open.