Toxic algae found in the Aparima and Oreti Rivers

Environment Southland’s latest monitoring has found elevated levels of toxic algae in the Aparima River at Thornbury and the Oreti River at Winton Bridge.

Environment Southland science strategy and investigations manager Dr Elaine Moriarty advised that there are already alerts in place for several Southland rivers and toxic algae could be present in other rivers as well. “People should take extra care when choosing a swimming spot or letting dogs off leads along rivers,” she said.

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 water 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.

Alerts are already in place for the Hamilton Burn at Affleck Road and the Waikaia River at Waikaia.

Toxic algae, or benthic cyanobacteria, can be recognised at rivers and streams as a black/brown slime on rocks, or dark brown/black mats at the water’s edge. These mats can become detached following heavy rainfall and flow downstream.

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.