MEDIA RELEASE

November 21, 2013

Health alert – algal bloom Lake Te Waiwera/Forsyth

The Community and Public Health division of Canterbury District Health Board has issued a health warning after potentially toxic blue-green algae (planktonic cyanobacteria) was found in Lake Te Wairewa/Forsyth.

People and animals, particularly dogs, should avoid Lake Te Wairewa/Forsyth until the health warning has been lifted.

The type of cyanobacteria that is currently present in high concentrations is Anabaena. Anabaena forms green globules that float in the water column.

Dr Alistair Humphrey, Canterbury Medical Officer of Health, says the algal bloom can produce toxins harmful to humans and animals and contact with the water should be avoided until further notice.

“Exposure may 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 the lake water,” Dr Humphrey says.

“Animals that show signs of illness after coming into contact with algal mats should be taken to a vet immediately.”

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

Dr Humphrey says nutrient overload, especially nitrate and phosphorous levels, can contribute to the risk associated with the development of toxic algae blooms in lakes.

Consumption of fish and shellfish should also be avoided as they can concentrate toxins.

“If fish are eaten, remove the gut and liver and wash in clean water,” Dr Humphrey says.

Environment Canterbury monitors the lake weekly during summer and the public will be advised of any changes in water quality that are of public health significance.

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.
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For further information visit http://ecan.govt.nz/services/online-services/monitoring/swimming-water-quality/Pages/lake-warnings.aspx Or contact Community and Public Health on (03) 364 1777.

ENDS

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