Elevated levels of toxic algae has been found in the Waiau River near Excelsior Creek, downstream of the weir.

Environment Southland senior scientist Roger Hodson said Waiau river users and animals should “avoid contact with algal mats and remain alert in other parts of the river for algal growth or mats of algae floating in the water”.

Toxic algae (benthic cyanobacteria) can be recognised at rivers and streams as a green/brown slime on rocks, or dark brown/black mats at the water’s edge.

These algae can produce toxins that are harmful to people and animals if swallowed, or through contact with skin.

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People and animals (dogs in particular) should avoid contact with the river and be mindful of the potential health risks, until health warnings are removed.

Several factors can contribute to the growth of toxic algae, such as high levels of nutrients, run-off into waterways, a sudden increase in temperature, and low flows.

Environment Southland advises that anyone experiencing health symptoms after contact with contaminated water should visit a doctor immediately.

And if there are any concerns about animals consuming toxic algae or contaminated water, then they should be taken to a vet immediately.

In addition to weekly summer monitoring, Environment Southland monitors toxic algae monthly during the rest of the year at a number of river and lake sites across Southland.

Click here for further information www.es.govt.nz/toxic-algae