Potentially toxic algal bloom is threatening yet another South Canterbury river.
Community and Public Health issued a warning late yesterday after water surveys of the Pareora River, at Pareora Huts, found "relatively high" levels of the algae, also known as phormidium.
It is the second river in as many weeks to be found with the algae. High levels were found in the Opihi River at Waipopo, last week.
However, warnings were lifted at the Black Hole and Don's Hole swimming areas on the Waihao River.
People and animals, particularly dogs, should avoid the areas still affected until the health warnings are lifted.
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 immediately," he said.
"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 water from the river at any time.
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