Council is warning the public to watch out for toxic algae in the Wairau River.

Environmental Scientist Steffi Henkel said Council’s team did a drift dive down the Wairau River yesterday and noted a significant spread of toxic algae in some parts of the river upstream from the SH1 bridge.

“The spread of toxic algae is caused by prolonged dry weather which results in consistently low river flows. With so many access points to the Wairau River, it is impossible to put signs up everywhere, but it is important for the public to be vigilant when walking their dogs along rivers and streams and to keep an eye out for the toxic algae.”

Toxic algae can pose a significant risk for dogs and small children. Council is asking people to avoid areas of water where it is present.

The algae form thick brown or black mats on rocks in the riverbed. These mats have a velvety appearance and can become detached from the rocks. They often accumulate along the water’s edge, where they decay releasing a musky odour, which dogs are attracted to.

“The toxins in the algae can be dangerous for children and dogs. If your dog ingests toxic algae, you should take it to the vet immediately. Symptoms usually occur within 30 minutes and include panting, lethargy, muscular twitching, paralysis, and convulsion.”

“In humans, contact with toxic algae can cause vomiting, diarrhoea and skin irritation,” Ms Henkel said.

The absence of a warning sign in other rivers and streams around Marlborough does not mean that toxic algae are not present.

Ms Henkel said the toxic algae cover in the Rai River had reduced to almost no cover and warning signs will be removed from that site. “The other waterway which had significant toxic algae cover earlier this season was the Omaka River but that waterway is now dry.”

You can find out more about toxic algae, including how to identify it, on Council’s website: www.marlborough.govt.nz/recreation/swimming-and-boating/toxic-algae

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