In a statement this morning, Environment Southland said monitoring had revealed algae in the Upukerora River at Te Anau/Milford Road.
Other alerts were in place for the Whitestone River downstream of Manapouri-Hillside Rd and the Waiau River near the Excelsior Creek inflow.
"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."
The algae looked like dark green/brown slime on rocks or dark brown/black mats at the water’s edge.
"Water users should be vigilant and avoid contact with the algae."
Environment Southland said it could not monitor everywhere, and there could be similar algae growth in other waterways in the area and other rivers in the region.
Toxic algae can pose significant health risks to people and animals if swallowed or through contact with the skin.
Dogs should be kept on the lead and children away from affected areas.
People should see a doctor immediately if they experienced health symptoms after contact with contaminated water.
"Take your animals to a vet immediately if they have consumed toxic algae or contaminated water."
River users were encouraged to keep informed via Environment Southland's website: www.es.govt.nz/toxic-algae
- APL
