Blue-Green Algae Monitoring

• Alert Levels
• Sampling Sites and Signage
• Results
• Bacteria Monitoring
• For more Information ...

Throughout the year the Environment Protection Authority (EPA) monitors the water quality at various sites in Lake Tuggeranong, Lake Ginninderra, the Molonglo River, Gungahlin Lake, Yerrabi Pond and Point Hut Pond. (Lake Burley Griffin is managed by the National Capital Authority.

Blue-green algae grow naturally in Australian fresh and saline waters. They are usually found in low numbers. However, when environmental conditions are favourable their numbers increase rapidly creating a 'bloom'. Drought conditions, high summer temperatures and high nutrient levels are all important factors in creating the conditions to cause algal blooms.

Blue-green algae in very large numbers cause deterioration in water quality and pose a threat to public health. As blue-green algae die they can release toxins into the water. These toxins can cause symptoms such as eye or skin irritations, sore throats or gastro-enteritis in humans.

The Blue-Green Algae in Recreational Water Management Strategy (the strategy), issued in December 2009, provides a framework for the managment of recreational activity in ACT lakes and rivers.  The strategy breaks down recreational use into two catagories, primary and secondary contact recreation. 

Primary contact recreation: This involves whole-body contact in which the entire body or the face and trunk are frequently immersed or the face is frequently wet by spray, and where it is likely that some water will be swallowed, inhaled, or come into contact with ears, nasal passages, mucous membranes or cuts in the skin (e.g. swimming, diving, waterskiing, windsurfing).

Secondary contact recreation: This may involve incidental contact in which only the limbs are regularly wet and in which greater contact is unusal (e.g. boating, fishing, canoeing, rowing). There may be occasional and inadvertent immersion through accidents (e.g. slipping into the water).

The following alert system is included in the strategy.

Alert Levels

Low Level Alert

At this alert level, there is generally no major health risk. Algal counts are between 500 to 5,000 cells per millilitre of lake water (0.04 to 0.4 mm³/L Biovolume).

Medium Level Alert

At this level, algal counts are between 5,000 to 50,000 cells per millilitre (0.4 to 4 mm³/L Biovolume) and scumming is ususally evident. There can also be a slight milky discolouration of the water and bright green surface scums.

When algal counts are above 20,000 cells per millilitre (1.6 mm³/L Biovolume) there is a greater risk of potential health problems.  At this level and on advice from the Health Protection Service, the EPA issues media warnings; erects WARNING signs; alerts sporting groups such as yachting, rowing and swimming clubs, as well as organisers of water sport events; and notifies the Water Police.

High Level Alert

At this level there is a higher risk of health problems. Algal counts are between 50,000 and 125,000 cells per millilitre (4 to 10 mm³/L Biovolume) and extensive scums have formed.

On advice from the Health Protection Service, the EPA may close recreational areas and the lakes for primary contact use. If the EPA closes a lake because of the severity of the blue-green algal bloom, it will place LAKE CLOSED signs around the lake; issue a media release; continue intensive monitoring until algal counts decrease to levels below 50,000 cells per millilitre of lake water; provide the community with regular reports about the condition of the lake or river recreation area; and communicate re-opening of the lake or waterbody for primary use by a media release.

Extreme Level Alert

At this level there is an extreme level of risk of health problems. Algal counts are above 125,000 cells per millilitre (greater than 10 mm³/L Biovolume), extensive scums have formed and environmental conditions suggest that algal numbers are likely to escalate quickly and become widespread throughout the water. The lake is closed for primary use and the risks assiciated with secondary contact use may be reduced provided steps outlined in the strategy are followed.

Sampling Sites and Signage

Permanent signs have been erected at various public use areas by the Environment Protection Authority. These signs are hinged, enabling them to display WARNING, LAKE CLOSED or are able to be closed when blue-green algae is not present.

The location of the sampling sites and signs is shown on the maps below:

Lake Ginninderra ( JPG 338Kb )

Lake Tuggeranong( JPG 374Kb )

Molonglo Ski Area ( JPG 230Kb )

Gungahlin Pond( JPG 364Kb )

Yerrabi Pond( JPG 287Kb )

Point Hut Pond ( JPG 286Kb )

Results

The results for each location as of 15 July 2010 are as follows (always be sure to check the signs at the lakes for the latest information):

Bacteria Monitoring

The ACT Health Protection Service conducts monitoring for bacterial pathogens at a number of sites in Lake Tuggeranong, Lake Ginninderra and the Molonglo River on behalf of Parks, Conservation and Land. Parks, Conservation and Land is responsible for warning the public if required. Any enquiries related to bacteria monitoring are directed to Canberra Connect on 13 22 81.

For more information ...

• General Information
• What are toxic algae?
• What causes toxic algae?
• Problems caused by toxic algae