​Toxic algae signs to support public education

Environment Southland has erected temporary signage at river and walking track access points across the region to remind people to be on the lookout for toxic algae in waterways.

Senior surface water scientist Katie Blakemore said algae blooms were a naturally occurring phenomenon and difficult to predict.

“Algae can flourish during fine conditions and stable river flows. Most algae are harmless; however, some species can produce toxins that can be harmful to people and animals,” she said.

People should check for dark green-brown slime on rocks and dark brown-black mats at the water’s edge.

Dogs were particularly susceptible and were often attracted by the smell.

As exposure could be lethal for dogs the best advice is to keep them on a lead around waterways until you have checked it is safe.

“We can’t monitor everywhere all the time so we’re hoping the signage will help raise awareness,” she said.

Toxic algae can occur year around. Information on what to look for is on the Environment Southland website (www.es.govt.nz/toxicalgae) along with any current warnings. People can also download the Antenno app to receive relevant alerts directly on their mobile phone.

Currently there are toxic algae alerts in place at the Waiau River near the Excelsior Creek inflow and the Waihopai River at Kennington.

Similar algae growth may be occurring in other waterways in these areas and other waterways in the region.

During 2023-2024 there were 15 alerts issued for waterways around Southland; up from 13 alerts in 2022-2023 and 12 the previous year.