Environment
Environment Southland has confirmed the presence of toxic algae in the Mataura River, specifically downstream of the Riversdale bridge. The discovery follows routine monitoring, which identified concerning levels of algae that may pose risks to both people and animals using the river.
Algae are a natural part of river ecosystems and are often harmless. They tend to grow more rapidly during periods of fine weather and when river flows remain steady. However, certain types can produce toxins and quickly increase to dangerous levels, creating potential hazards in affected areas.
Toxic algae can usually be recognised by their appearance. They often form as dark green or brown slime on rocks within the river, or as dark brown to black mats along the water’s edge. Authorities are urging anyone visiting the river to stay alert and avoid touching or entering areas where this algae is visible.
Health risks linked to toxic algae include illness following ingestion or skin contact. People who come into contact with contaminated water and begin to feel unwell are advised to seek medical attention immediately. The warning also extends to animals, particularly dogs, which are at higher risk due to their tendency to drink from or play in rivers. Pet owners should keep dogs on leads and away from affected areas, and seek veterinary care if exposure is suspected.
Environment Southland has stressed that it cannot monitor every waterway across the region. As a result, similar algae growth could be present in other rivers and streams nearby. River users are encouraged to remain cautious wherever they go and to familiarise themselves with the signs of toxic algae.
To support public awareness, Environment Southland is directing people to its website, where detailed information, images, and updates are available. These resources aim to help individuals identify potential risks and make informed decisions when using local waterways.