What are Blue-Green Algae?

Blue-Green Algae (also called Cyanobacteria) are microscopic photosynthetic bacteria that are natural inhabitants of our waterways, estuaries and the ocean. Some blue-green algae (BGA) species are toxic and can release toxins into the water.

There is a concern that the toxins may cause illness in humans and animals. Some algae species also release compounds which impart earthy tastes and odours into the water. In still water such as lakes, ponds and reservoirs these algae may multiply exponentially, especially in summer months in response to increased water temperatures causing the water to become discoloured with a green, blue-green or greenish-brown appearance.  This discolouration may have been observed in some still areas of Lake Awoonga. The Gladstone Area Water Board (GAWB) undertakes regular visual inspections and regular water monitoring as part of its water quality monitoring program and storage management operations.

GAWB also undertakes visual surveys for scum and flocs of BGA which could occur during calmer weather if the BGA rises to the water surface. Flocs sit on the surface of the water or the shoreline and may disappear and reappear on subsequent days and as a result of wind action. Not all species at Lake Awoonga form scums and their blooms may not be clearly visible.

Blue-green Algal blooms are very common over summer in farm dams, lakes, estuaries and in slow moving rivers in all states of Australia.

The GAWB Blue-Green Algae Action Plan was reviewed and updated in 2009, based on DNRW guidelines, Australian Drinking Water guidelines and on advice from BGA experts.

Levels of BGA in Lake Awoonga are not significantly different from the levels in other Queensland lakes during the hot still summer months. Signage at various locations around the Lake indicate the current blue-green algae level to recreational users.
 

Drinking Water & Recreational Activities

Drinking untreated water directly from Lake Awoonga or any lake or river is not advisable if BGA concentrations are elevated. Water from Lake Awoonga is treated at either the Gladstone or Yarwun Water Treatment Plants and dispatched by Gladstone Regional Council for drinking.

The effect of ingesting BGA in water is still not clearly understood. As a precaution, bathing, swimming or showering in water with high concentrations of BGA should be avoided.

Water entering and leaving the water treatment plants is stringently monitored by GAWB, and Queensland Health regularly audits tap water. Treatment is tailored to remove toxins through flocculation, filtration, chlorination and if necessary with the addition of powder–activated carbon.

Any concerns about the potable water supply should be directed to your local council.

Agricultural Use

There are beef producers and agricultural users in the region who source their water directly from the Boyne River and its tributaries. Algal scum or visibly discoloured water may be toxic to livestock and domestic animals. Farmers should prevent access to affected water and provide alternative supplies. Generally algae do not affect the suitability of waters for irrigation.

Wildlife

Apart from freshwater mussels and the organs of aquatic animals, consumption of game and fish that has been in contact with algal infested water can be considered safe.

University studies on the meat of barramundi, red-claw and mussels from Lake Awoonga have been undertaken. Results indicate that barramundi and red-claw meat is safe to eat, provided it is washed in clean water and the organs removed. As a precaution though, it is recommended that mussels not be consumed.