The Community and Public Health division of Canterbury District Health Board
have issued a health warning this week after toxic blue-green algae (planktonic
cyanobacteria) were found in Lake Forsyth/ Te Wairewa.
People should stay out of the water at this site until the health warnings
have been lifted. Toxic algae are particularly dangerous for dogs, so they
should be kept away from the water.
Canterbury Medical Officer of Health Dr Alistair Humphrey says the algal
bloom can produce toxins harmful to humans and animals.
“Exposure may cause skin rashes, nausea, stomach cramps, tingling and
numbness around the mouth and fingertips. If you experience any of these
symptoms after contact with contaminated water, visit your doctor immediately,”
Dr Humphrey says.
“No one should drink the water from the lake at any time, even if it has been
boiled because boiling does not remove the toxin.
Animals should be taken to a vet immediately if they come into contact with
water contaminated by the algal bloom or if they display any unusual
Fish and shellfish can concentrate toxins and their consumption should be
Environment Canterbury monitors this site weekly during summer and the public
will be advised of any changes in water quality that are of 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.
For further information visit Environment Canterbury.
Or contact Community and Public Health on (03) 364 1777.
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