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Pegasus Lake Algae Warning Lifted

Subject: CDHB Media Release - Health warnings removed from two Canterbury lakes


Health warnings removed from two Canterbury lakes

22 April 2015

The Community and Public Health division of the Canterbury District Health Board has lifted its algal bloom health warnings for Lake Forsyth and Pegasus Lake.

Both warnings were issued in February 2015.

Recent water testing at Lake Forsyth and Pegasus Lake have shown the quantity of potentially toxic blue-green algae (planktonic cyanobacteria) has decreased and concentrations are now below the levels that are of concern to public health.

Canterbury Medical Officer of Health Dr Alistair Humphrey says as we move into winter there is a decreased chance of the toxic algae returning until the warmer months.

Both lakes will continue to be monitored on a monthly basis and the public will be notified if there is a risk to public health.

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). If a health warning is in place avoid contact with the water.

If a warning is in place, people and animals should not drink the water from the lake at any time, even boiled water.

Exposure to an algal bloom can cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips. If you experience any of these symptoms visit your doctor immediately and please let your doctor know if you have had contact with lake water when there is a health warning in place.

For further information visit

Or contact Community and Public Health on (03) 364 1777.

Media queries can be directed to Canterbury DHB Communications Advisor Donovan Ryan on 0273444011

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