Tuesday 26 January 2021Media release3 minutes to read
Canterbury District Health Board’s Community and Public Health unit has issued a health warning for Selwyn/Waikirikiri River at Coes Ford.
The warning follows finding moderate to high cover of potentially toxic algae (benthic cyanobacteria) in the Selwyn/Waikirikiri River.
People and animals, particularly dogs, should avoid the area of the Selwyn/Waikirikiri River until the health warning has been lifted.
There are also other access points along the Selwyn/Waikirikiri River that may have benthic cyanobacteria present.
People are advised to treat every low-flowing river cautiously, check for the presence of benthic cyanobacteria and avoid contact.
Dr Ramon Pink, Canterbury Medical Officer of Health, says the algae look 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 Pink says.
“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.
Pets that show signs of illness after coming into contact with algal mats should be taken to a vet immediately.
People and animals should remain out of the waterways until the warnings have been lifted.
Environment Canterbury is monitoring the sites and the public will be advised of any changes in water quality.
Facts about cyanobacteria:
For further information visit
Or contact Community and Public Health on (03) 364 1777:
For more information about Mahinga Kai:
Page last updated: 19 August 2021
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