Toxic algae red alerts in Kāpiti, Wairarapa and Hutt rivers

  • Published Date 27 Mar 2026
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  • Water quality

Red alert level warnings are in place for the Waikanae River, Ruamāhanga River, Waipoua River and Te Awa Kairangi (Hutt River) due to toxic algae levels.

Greater Wellington advises people not to swim or let their dogs near the water at the following sites.

  • Waikanae River at Jim Cooke Park due to high levels of toxic algae and detached mats starting to form. 
  • Te Awa Kairangi (Hutt River) at Silverstream due to high levels of toxic algae and detached mats starting to form.
  • Waipoua River at Colombo Road due to moderate levels of toxic algae and widespread detached mats accumulating at the river’s edge.
  • Ruamāhanga River at Double Bridges and Te Ore Ore due to moderate levels of toxic algae and the presence of detached mats accumulating at the river’s edge.

Toxic algae is a neurotoxin that acts like snake venom, which can be very harmful to humans and lethal for dogs if ingested. Even a small amount of toxic algae, the size of a 50-cent piece, can be enough to kill a dog.

If you think your dog has swallowed toxic algae, or it shows signs of lethargy, muscle tremors, fast breathing, paralysis or convulsions, should go to the nearest vet immediately.

People who have been in contact with toxic algae and are feeling unwell, should see a doctor or ring Healthline on 0800 611 116. 

People are advised to check the LAWA website for toxic algae warnings and alerts before visiting rivers in the Wellington region. 

Greater Wellington is currently monitoring popular river swimming spots for toxic algae on a weekly basis.

Toxic algae under the water; dark brown-green mats clinging to rocks
Toxic algae at Double Bridges
Toxic algae under the water; small green-brown mats partially clinging to rocks and partially detached
Toxic algae at Te Ore Ore
Toxic algae under the water; small green-brown mats partially clinging to rocks and partially detached
Toxic algae at Te Ore Ore
Updated March 27, 2026 at 9:55 AM

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Email:
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