Warnings after toxic algae found in two Canterbury rivers

Pet owners are being warned to keep their dogs away from two Canterbury rivers due to toxic algae.

Community and Public Health has issued warnings telling people to avoid the Opihi River and the Rakahuri/Ashley River, particularly around State Highway 1.

Environment Canterbury said the algae (benthic cyanobacteria) is very toxic to dogs and animals should not be allowed near the water until the health warnings have been lifted.

Other access points along the rivers may also be affected by the algae.

People are advised to treat every low-flowing river cautiously, check for the presence of benthic cyanobacteria and avoid contact.

The consumption of fish and shellfish should also be avoided. If fish are eaten, remove the gut and liver and wash it in clean water. No one should drink the water from the rivers at any time and boiling the water does not remove the toxin.

Canterbury Medical Officer of Health Dr Cheryl Brunton said the algae appears as 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.”

“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 should be taken to a vet immediately. ECan is monitoring the sites for any changes.