High concentrations of Blue-Green algae have been found at Castle Semple Loch.
Swimming in the loch is not advised. Most watersports activities such as sailing, rowing and kayaking can generally avoid any scum formations.
Swallowing the water or algal scum can cause stomach upsets or more serious health effects. Contact with the water or with algal scum can cause skin problems. Algal scums may be harmful. As a precaution any person or animal should avoid contact with blue-green scum and water close to the scum.