Algae appear as dark brown/black mats attached to rocks along the riverbed

Toxic algae warning — Selwyn River

by Mike Isle

Canterbury District Health Board’s Community and Public Health unit has issued a health warning after potentially toxic blue-green algae was found in Selwyn/Waikirikiri River downstream of the popular Glentunnel swimming hole.

People and animals, particularly dogs, should avoid the area until the health warning has been lifted.

There are also other access points along the river that may have algae present and people are advised to check for the presence and avoid contact.

Dr Alistair Humphrey, Canterbury Medical Officer of Health, said the algae looks like dark brown to black mats and can produce toxins harmful to people and animals.

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

“If you experience any of these symptoms, visit your doctor immediately, also let your doctor know if you’ve had contact with dark brown/black algal mats or water in this area.”

“No-one should drink the water from the river at any time, even after boiling the water from the river, it does not remove the toxin, therefore, should not be consumed,” Dr Humphrey said.

The Selwyn District Council, as the drinking water supplier, is following agreed procedures and monitoring their nearby drinking water intakes.

Pets should be taken to a vet immediately if they are showing signs of illness after coming into contact with algal mats.

Environment Canterbury is monitoring the sites, and the public will be advised of any changes in water quality. People and animals should remain out of the waterways until the warnings have been lifted.