Toxic Algae present in Wai-iti and Takaka Rivers

The Tasman District Council’s summer toxic algae monitoring programme has reported toxic algae in the lower Wai-iti River, the Waimea around River Road, and in the Takaka River from Paynes Ford down past Reilly’s Road. While no incidents relating to exposure have been reported people should take a precautionary approach especially with small children and dogs near the water if the algae is visible.

The algae that is of most concern is relatively distinctive, forming mats that are soft, dark coloured (black, dark green or dark brown), sometimes thick (over 3mm) and somewhat jelly-like. They are typically found on stable substrate such as large rocks, stones and cobbles. The mats often smell musty, hence are attractive to dogs.

The algae is known to be deadly to dogs and poses a potential health risk to humans, with exposure to the toxins capable of causing vomiting, diarrhea, abdominal pain, cramps, and nausea. It is wise to not enter the water where the algae is visibly building up.

In slow moving parts of the river the algae may appear like 'dreadlocks' when it gets caught on tree roots and continues growing. It may come loose from the riverbed and form floating 'rafts', which become caught in other debris in the river. When the toxic algae mats die and dry out they become light brown or white in colour.

The more brightly-coloured long filamentous green algae that is commonly found in rivers and streams are harmless algae that do not produce toxins.

Anyone concerned about toxic algae, or who wishes to report a site where algae is present, can contact the Council any time on Ph. 03 543 8400. A photo of the algae and/or the site would also be helpful.

More information is available on the Council’s website: www.tasman.govt.nz/environment/water/rivers/river-water-quality/monitoring-toxic-algae

ENDS

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