Health officials have warned people to stay away from a Banks Peninsula lake after toxic blue-green algae was found in it.
Health New Zealand Te Whatu Ora issued the official warning after the potentially toxic algae, planktonic cyanobacteria, was found in Lake Forsyth/Te Roto o Wairewa.
The algae is particularly harmful to children and dogs and they should not be allowed near the water until the health warning has been lifted.
Public Health Medicine Specialist Dr Annabel Begg said in a statement the cyanobacteria currently present in high concentrations at the lake is nodularia, which can appear as a thick surface scum.
Begg said 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." Begg 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.
“When a bloom of potentially toxic cyanobacteria is present in a lake, there is a possibility of cyanobacteria and toxins being transported downstream.
“People are advised to avoid contact with the downstream water bodies,” said Begg.
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.
Toxic algae. Photo: Environment Canterbury
What is cyanobacteria?
Toxic blue-green algae occurs 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 such as 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.
