Watch for Algal Blooms

Hawke’s Bay District Health Board is reminding people to take care around streams, rivers and lakes following the detection of algal blooms at three sites along the Tukituki River.

Hawke’s Bay District Health Board Medical Officer of Health, Dr Caroline McElnay said Hawke’s Bay’s summer weather conditions, resulting in lower river flows and warmer water temperatures, increased the likelihood of algal blooms in the region’s fresh waterways, which can be toxic to humans and dogs.

Dr McElnay said Hawkes Bay Regional Council staff had already observed cyanobacterial mats (algal blooms) at three sites in the Tukituki River - Patangata, Red Bridge and Horseshoe Bend. Whilst the algal were not at levels where an official health warning needed to be issued, signs had been erected to advise people that algal blooms had been detected in those areas and to be cautious.

The algae exist in rivers naturally, but can form mats in continuing warm, dry weather and low river flows. These mats can become toxic. Particular caution needs to be taken with algal mats that are floating on the surface or washed up on the river’s edge.

Dr McElnay said algal mats are identifiable by a strong musty odour and can vary in colour from dark green/brown to a pale brown/whitish colour when dry.

“Any contact with a toxic form of the algal mat may cause vomiting, diarrhoea and skin irritations in humans,” said Dr McElnay.

“Dogs are particularly susceptible to the toxins, and owners are advised to avoid allowing their dogs to scavenge on the river’s edge.”

Dr McElnay said swimming should be avoided in the detected areas.

“Anyone who displays signs of illness after being in a river bed should seek medical advice from a doctor immediately,” said Dr McElnay.

“Similarly, any dogs or other animals that get sick after being in a river should get prompt veterinary attention,” she said.

Hawke’s Bay Regional Council would continue monitoring the site on a weekly basis and the public would be advised of any changes in algal mat coverage.

-ENDS-

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