Toxic algae red alerts in Kāpiti and Hutt rivers

  • Published Date 09 Apr 2026
All Tags
  • Environment
  • Water quality

Red alert level warnings are in place for the Waikanae 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 where red alerts are in place.

  • 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 and Poets Park due to high levels of toxic algae and detached mats starting to form.

Amber alerts are in place at other sites due to moderate levels of toxic algae – people should exercise caution if swimming and keep dogs on leads and away from the river’s edge at the following sites.

  • Waingawa River at South Road due to moderate levels of toxic algae.
  • Ruamāhanga River at The Cliffs, Double Bridges and Te Ore Ore due to moderate levels of toxic algae.
  • Te Awa Kairangi (Hutt River) at Birchville due to moderate levels of toxic algae 

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 seen from above the water - irregular black mats spreading across the bottom of the river
Toxic algae at Double Bridges on the Ruamāhanga River
Toxic algae under the water; dark brown-green mats clinging to rocks
Toxic algae at Birchville on Te Awa Kairangi (Hutt River)
Updated April 9, 2026 at 3:35 PM

Get in touch

Phone:
0800 496 734
Email:
info@gw.govt.nz