The U.S. Army Corps of Engineers’ (USACE) Philadelphia District is advising visitors to Blue Marsh Lake to be aware of the presence of extremely high levels of blue-green algae in the lake and the potential for harmful toxins to be present. Due to the high levels of algae in the lake, the Swim Beach at the Dry Brooks Day Use Area will be closed. Additionally, visitors are advised to avoid contact with the lake water until further notice.