Blue-green algae are a type of bacteria known as Cyanobacteria. Most blue-green algae species are safe or non-toxic, however some species are considered toxic and care should be taken to eliminate any contact with the affected water body.
The term algal bloom is used to describe a large number of cells that discolour the water bluey-green. It can be thick and have an unpleasant taste and smell.
Blue-green algae can occur in rivers, dams, lakes such as Blackburn Lake or Surrey Dive. The algae occurs more often when the water is still and the weather or water is warm.
Algal blooms take oxygen out of the water which can kill fish and harm other animals.
Blue-green algal blooms often last for several weeks, sometimes months, depending on the weather and water flow conditions.
As the bloom dies, the cells tend to become 'leaky' and, if the algal bloom produces toxins, the toxins will be released into the surrounding water. Once released, some toxins may persist in the water for more than three months.