Toxic algae increasing throughout the region

  • Published Date 24 Jan 2020

Toxic algae has been found at a number of sites throughout the region and people should pick their swimming and dog walking spots carefully to avoid the risk to health from contact with the algae.

Monitoring by Greater Wellington Regional Council has found that levels of toxic algae are likely to continue to rise in the face of warm weather forecast for parts of the region over the coming week.

Key places to avoid are: the Waipoua River, where there is an extensive bloom and detached mats of algae; and the Waikanae River, where the Jim Cook Park monitoring site shows some detached mats.

Warning signs remain in place at the Waipoua and Waikanae rivers and people are strongly advised to avoid the Waipoua River where toxic algae and detached mats are widespread.

Levels are also rising on the Hutt River and swimming should be avoided at Silverstream. People should exercise caution at other points along the river and look out for evidence of toxic algae.

Toxic algae grows on submerged river stones, presenting with a shiny brown/dark green to violet coating. It can also become unstable and detach, floating to the surface forming small brown/black mats at the water's edge.

It is important to keep an eye on babies and toddlers who may put objects in their mouths. Seek emergency medical attention immediately if anyone in your group swallows toxic algae.

If you have been swimming in a river or lake and you have any of the following symptoms: nausea, vomiting, numbness, tingling, muscle twitches, shaking, weakness, breathing difficulties and potentially convulsions and loss of consciousness see your doctor immediately.

Caution should also be taken when exercising dogs by rivers as they are strongly attracted to the musty smell of drying mats and will eat them where they can, which could be fatal.

Before you swim, stay safe by finding out about toxic algae

More information on where it is safe to swim.

Updated September 20, 2023 at 4:18 PM

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