Algal bloom warning for Lake Pegasus

Tuesday February 14, 2017

​Community and Public Health (a division of Canterbury District Health Board) has issued a health warning after potentially toxic blue-green algae (planktonic cyanobacteria) were found in Lake Pegasus.

Canterbury Medical Officer of Health Dr Ramon Pink, says the algal bloom can produce toxins harmful to humans and animals.

"People and animals, particularly dogs, should avoid contact with Lake Pegasus until the health warning has been lifted," Dr Pink says.

"Exposure may cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips. Visit your doctor immediately if you experience any of these symptoms - please let them know you have had contact with the lake water."

No one should drink the water from the lake at any time, Dr Pink says. Boiling the water does not remove the toxin.

"This bloom will be monitored on a weekly basis and the public will be advised of any changes that are of public health significance," he says.

Facts about cyanobacteria:

  • The algae occur naturally but can increase rapidly during warmer months.
  • If the water is cloudy, discoloured, or has small globules suspended in it, avoid all contact.
  • Not all cyanobacterial blooms are visible to the naked eye and toxins can persist after the blooms disappear.
  • Cyanobacterial concentrations can change quickly with changing environmental conditions (e.g. wind).
  • Avoid contact with the water if a health warning is in place.

Visit the Environment Canterbury website for more information on swimming water quality in Canterbury.

You can also contact Community and Public Health on (03) 364 1777.

Page last reviewed: 14 February 2017
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