Canterbury DHB’s Community and Public Health unit has issued a health warning after potentially toxic blue-green algae
(planktonic cyanobacteria) was found in Te Roto o Wairewa – Lake Forsyth.
People should avoid the Lake and animals, particularly dogs, should not be allowed near the water until the health
warning has been lifted.
Dr Cheryl Brunton, 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. 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 Brunton says.
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 or scums 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. Further information on gathering Mahinga Kai can be obtained below.Facts about cyanobacteria:Cyanobacteria occur naturally but can increase rapidly during warmer months.Algal blooms are caused by a combination of nutrients in the water (such as nitrogen and phosphorus), and favourable
weather conditions (e.g. increased temperature, calm days).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.