Another section of the Opihi River is out of bounds to people and animals after more potentially toxic algae was found.
Community and Public Health issued the warning for the Opihi River at SH1 yesterday.
There is also a warning in place for the river at Waipopo, the Pareora River near Pareora Huts and The Black Hole, a popular swimming spot on the Waihao River. Those warnings were issued over the past couple of months.
People and animals, particularly dogs, should avoid all affected areas until the warnings have been lifted. No-one should drink the water from the rivers at any time. Boiling the water does not remove the toxin.
Canterbury medical officer of health Dr Daniel Williams said exposure could cause skin rashes, nausea, stomach cramps and tingling and numbness around the mouth and fingertips.
"If you experience any of these symptoms, visit your doctor. Also, let your doctor know if you've had contact with the dark brown/black algal mats, or water in this area."
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