Toxic algae has been found in the Waiau River near Tuatapere and Waihopai River at Kennington, Environment Southland (ES) reports.

Toxic algae blooms, which usually occur over summer or when rivers are low, produce toxins (called cyanotoxins) that are harmful to animals and humans when eaten, licked, or when water containing the toxins is swallowed.

Some people can also have an allergic reaction when they touch the algae.

ES conducts monthly monitoring for toxic algal blooms across Southland.