Anglers are advised to be aware that blooms of blue green algae may occur at certain inland waters during the warmer summer months. The Inland Fisheries Service recommends anglers observe any public health notices regarding the risk from skin contact with the water where blue green algae blooms have been identified.

Monitoring of toxicity of blue green algal blooms is undertaken by relevant government health authorities. Their advice is provided through written advisories which are erected on site where the concerns for public health exist.

As water temperatures increase over summer, there is an increased likelihood of blue green algal blooms. There are a number of different species of blue green algae which occur naturally in our waterways and the blooms are associated with elevated water temperatures and other characteristics of certain water bodies. They typically occur in shallow lowland waters with high nutrient loads and may spread between connected systems.

The potential toxicity to humans caused by blue green algae varies according to the species, the density of cells within the bloom and the life stage of the bloom (eg whether the cells have died off and are breaking down). In some cases, there is little risk from skin contact or eating fish from water containing a bloom while in other situations, the toxicity may be greater.

Blue green algae was identified at Four Springs Lake in mid December and a public warning was placed by the Meander Valley Council beneath the Inland Fisheries sign adjacent to the boat ramp. Further sampling, including toxicity testing, was taken more recently and the species does not appear to be toxic.

A high bio-volume of blue green algae cells was also identified at Woods Lake in early January. Although this lake is situated in the Central Highlands, it has a history of elevated water temperatures and cyanobacterial counts. Monitoring by Hydro Tasmania is ongoing and local health authorities will advise regarding any risk to public health from recreation or drinking water containing the algae.

The IFS will keep anglers posted regarding the outcome of monitoring of these and other waters via the website.