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April 09, 2026
#regional: Red alert issued as toxic algae spreads across Kāpiti and Hutt rivers
Matthew Tukaki
Posted On April 9, 2026
Residents are being warned to stay out of several rivers across the Wellington region as toxic algae reaches dangerous levels in Kāpiti and the Hutt Valley.
Red alert warnings are now in place for parts of the Waikanae River and Te Awa Kairangi, along with waterways in Wairarapa, after monitoring found high concentrations of the harmful algae forming along riverbeds and edges.
Authorities say the algae produces a potent neurotoxin that can pose serious risks to human health and is especially dangerous for dogs, with even small amounts capable of causing fatal poisoning.
The greatest risk is where algae breaks away from rocks and collects along riverbanks, making it more accessible to children and animals.
People are being urged to avoid swimming, keep pets away from the water, and take extra care near affected sites, particularly popular recreation spots where algae has been detected.
Health officials advise anyone who comes into contact with the algae and feels unwell to seek medical advice, while dog owners are being told to get urgent veterinary help if their pets show signs of poisoning such as tremors, breathing issues or paralysis.
Monitoring of rivers across the region is continuing, with authorities checking conditions weekly as warmer weather and low river flows create ideal conditions for algae blooms to grow and spread.
The warnings highlight ongoing environmental pressures on waterways and the need for vigilance as conditions shift.
If you can see it, it’s already too dangerous to ignore.
Residents are being encouraged to check official water quality updates before heading to rivers and to avoid complacency as toxic algae levels fluctuate across the region.
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