Environment Southland’s latest monitoring has found elevated levels of the toxic algae in the Mataura River. 

The latest discovery is near the Mataura Bridge in Mataura and this follows confirmations that toxic algae is present in the Riversdale Bridge and Gore areas.

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. 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.

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Environment Southland science manager Dr Elaine Moriarty said Environment Southland monitors for toxic algae weekly during summer. “It’s really important that people know what to look for and take a cautious approach to swimming and walking dogs off-lead along rivers as we can’t assess every reach of every river.” 

Toxic algal blooms have plagued many lakes and rivers around the country this year, but this is the first confirmed bloom in Southland this summer. “Last year we alerted people to toxic algae in a number of rivers, but this year, we haven’t had the right conditions for it to bloom. Instead we’ve had rather unsettled weather and periodic rain which helps to flush any algae away.”

These algae can produce toxins that are harmful to people and animals if swallowed, or through contact with skin. People and animals (dogs in particular) should avoid contact with the Mataura River and be mindful of the potential health risks, until health warnings are removed. 

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 or contaminated water, 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.

For further information visit Environment Southland’s website HERE.

Media Release by Environment Southland