Te Mana Ora/Community and Public Health has issued a health warning for Opihi River at Saleyards Bridge after moderate to high levels of toxic algae (benthic cyanobacteria) were found.

Te Mana Ora medical officer of health Dr Cheryl Brunton said the algae looked like dark brown to black mats and could 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.”

Brunton said people should avoid the area and animals, particularly dogs, should not be allowed near the water until the health warning has been lifted, while other access points along the river could have benthic cyanobacteria present.

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

“Pets that show signs of illness after coming into contact with algal mats should be taken to a vet immediately.”

Environment Canterbury is monitoring the sites and the public will be advised of any changes in water quality.

Other sites in South Canterbury currently under temporary health warnings include:

Opihi River at SH1

Opihi River at Grassy Banks

Pareora River at Pareora Huts

Waihao River at Bradshaws Bridge

Waihao River at Gum Tree Road (Don’s Hole)

Hae Hae Te Moana River at Gorge