Environment Southland’s (ES) latest monitoring has found high levels of potentially toxic algae in the Upukerora River at Te Anau-Milford Road.

Environment Southland senior scientist Katie Blakemore said water users should be vigilant and avoid contact with the algae.

“This is a particularly popular spot for dog walkers and many people walk their dogs off the lead in the area."

Last year (29 Jan 2023) a local pet dog, Tora, died of suspected poisoning after coming into contact with the toxic algae in the same river.

"Pet owners should take extra care in this area, and all the way along the Upukerora River as ingesting just a small amount can be toxic to dogs.”

Algae naturally occur in waterways and can flourish during fine conditions and stable river flows. Most algae are harmless.

However, some species can produce toxins and rapidly bloom to high levels. These algae are potentially toxic, and commonly identified in waterways as a dark green/brown slime on rocks, or dark brown/black mats at the water’s edge.

Swimming at this location should also be avoided.

“These algae can produce toxins that are harmful to people and animals if swallowed, or through contact with skin. People should keep dogs on a lead and children away from affected areas. 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.

Similar algae growth may be occurring in other waterways in the area.

“We monitor toxic algae monthly during the year at a number of rivers and lakes sites across Southland. Potentially toxic algae blooms are more likely to occur in summer, but it can happen at any time of the year.”

There is also a toxic algae warning in place for the Waituna Lagoon.