January 29, 2015

Health Warning – Algal Bloom in Lake Forsyth/Te Wairewa

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 Forsyth/Te Wairewa

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

The type of cyanobacteria that is currently present in high concentrations is both:
· Nodularia which appears as a thick surface scum.

· Anabaena which forms green globules that float in the water column. Despite the difference in appearance, the potential health risks are similar and people should avoid contact with the water until further notice.

Dr Ramon Pink Canterbury Medical Officer of Health says the algal bloom can produce toxins harmful to humans and animals; people should avoid contact with the water until further notice.

“Exposure may cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips,” Dr Pink says.

“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.”

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

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

Fish and shellfish can concentrate toxins and their consumption should be avoided. If fish are eaten, remove the gut and liver and wash in clean water.

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.

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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