Health warning over toxic algal bloom renewed

Potentially toxic algal bloom is once again threatening The Black Hole, South Canterbury's popular swimming spot on the Waihao River.

Community and Public Health issued a warning for the area yesterday. It came after "relatively high" levels of the algae, also known as phormidium, were found.

The warning comes just two weeks after an initial warning was lifted. A warning was also lifted at Don's Hole, on the same river.

Warnings are still in place at Pareora Huts on the Pareora River and at Waipopo on the Opihi River.

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, [you should] visit your doctor immediately," he said.

"Also, let your doctor know if you've had contact with the dark brown/black algal mats, or water in this area," Dr Williams said.

The toxic phormidium appears as dark brown-black mats attached to rocks along the riverbed.

The Timaru Herald