Tasman District Council environmental scientist, Trevor James, with the signs that will be erected to warn dog owners of the dangers of cyanobacteria in the Wai-iti and Waimea rivers.

Toxic algae taking over Tasman rivers


Over the last week, toxic algae levels have grown in Tasman’s Waimea and Wai-iti rivers.

The latest results showing the algae’s growth to warning levels following a number of weeks of relatively low growth levels.

Regular river users who take dogs or toddlers down to play in the water are strongly advised to become familiar with what the toxic algae looks like and avoid contact when it is present.

The algae that are of most concern is distinctive, forming mats that are soft, dark coloured (black, dark green or dark brown), sometimes thick (over 5mm) and somewhat jelly-like.

The Council will place warning signs at the most popular sites if the algae reach levels exceeding 20%, which is currently the case in the Waimea and Wai-iti rivers.

Throughout the summer the Council’s toxic algae monitoring programme focuses on the Lee, Wairoa, Waimea and Motueka Rivers. Click Here for the latest toxic algae results.