Toxic algae found in the Mataura River

Environment Southland’s latest monitoring has found elevated levels of the toxic algae benthic cyanobacteria in the Mataura River near the Mataura Island Bridge.


Environment Southland director of science and information Graham Sevicke-Jones advised that with the warm weather it’s likely that toxic algae will be present in other areas along the Mataura and possibly other rivers in Southland. “People should take extra care when choosing a swimming spot or letting dogs off leads along rivers,” he said.

These algae can produce toxins that are harmful to people and animals if swallowed, or through contact with the skin. People and animals (dogs in particular) should avoid contact with the water and any mats that have formed at the waters’ edge.

If you experience health symptoms after contact with contaminated water, visit a doctor immediately. If you are concerned that any animals have consumed toxic algae mats or contaminated water, they should be taken to a vet immediately.

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

Environment Southland monitors toxic algae monthly at a number of river and lake sites across Southland.

For further information visit Environment Southland’s website www.es.govt.nz/toxic-algae.