Not all blue-green algae blooms are toxic but you cannot tell if a bloom is toxic by looking at it. If you see an algal bloom it is best to assume it is harmful and take the following precautions:
Anyone who has come into contact with water containing blue-green algae should shower with fresh water immediately. If you have come into contact or drunk affected water and feel unwell you should obtain medical attention. Symptoms generally begin within hours after exposure.
The toxins which may be produced by algae are also poisonous to animals and can cause severe illness and death. Farmers and pet owners should ensure that their animals do not have access to affected water.
Blue green algae mainly affect freshwater. Some types of marine algae in our seas can also form algal blooms and some of these can be toxic. For more information of Marine Algal Blooms please visit Natural Resource Wales website.