24 May 2012

Lake Burley Griffin is closed to activities that involve whole-body water contact or submersion of the head due to extreme levels of blue-green algae.

National Capital Authority chief executive, Gary Rake said there has been a significant spike in blue-green algae levels over the last week.

"Water quality results received today indicate blue-green algae levels are more than 1000 times higher than the level considered safe for activities such as swimming," he said.

Extreme levels of the blue-green algae strain, Anabaena circinalis have been recently detected.

"More worryingly, this is a very different strain of blue-green algae from the one we typically experience over the summer months. Lake users who engaged in secondary contact activities over summer need to carefully reassess the risks."

"We ask all secondary contact lake users to exercise extra caution. Inexperienced users, and people in unstable craft, should avoid going on to the lake until water quality improves. Falling into cold water, and being exposed to high levels of the Anabaena algae, could prove fatal," Mr Rake said.

ACT Health advises the Anabaena circinalis strain produces hepatotoxins and neurotoxins. Hepatotoxins attack the liver and other internal organs, and may also cause visual disturbances, gastroenteritis, nausea, vomiting and muscle weakness. Neurotoxins act as neuromuscular blocking agents. High levels of exposure can result in death by paralysis of peripheral skeletal muscles, then respiratory muscles, and respiratory arrest.

Secondary contact recreation, such as rowing, fishing, boating and canoeing will still be permitted, noting ACT Health's advice below:

• Symptoms of blue-green algae exposure may include skin/mucosa irritation, flu-like symptoms, and gastrointestinal illness
• There is an increased risk of adverse health effects from water exposure for secondary contact recreation
• People should not engage in secondary contact recreation unless:
  • They are experienced;
  • They are informed of the algal risks and what to do if contact occurs;
  • They do not engage in primary contact during the recreation; and
  • Showering facilities, with suitable water, are available for washing after the recreation
• Water users should shower after water contact;
• Event organisers should ensure that participants are aware of the blue-green algae alert level, associated exposure risks and provide adequate showering facilities for after events;
• Water users should look for algae warning signs indicating the current alert level at major water entry points as algal levels can change quickly depending on the weather and water nutrient levels

The Captain Cook Memorial Jet in Central Basin will remain off as winds can create fine mists and cause jet water to travel to areas around the lake, potentially exposing the public to algae either through direct contact with, or inhalation of, the mist.

Pet owners should not allow their animals to swim in or drink lake water.

Click here for weekly lake updates, information on water quality and the ACT Guidelines for Recreational Water Quality.