Toxic Algae

Community Engagement Advisor from Greater Wellington Regional Council

Ongoing monitoring of toxic algae in the Waipoua River at Colombo Road has confirmed that toxic algae cover is currently low, meaning the warning that has been place since before Christmas has been removed.

There is still a lot of algae in the river at this site, but the composition has changed. Most of the algae is a species of diatom – slimy but harmless. The close-up below shows a rock that is mostly covered by the diatom species – it’s yellowy/green and bumpy in appearance. You can also see a couple of patches of Phormidium or toxic algae. In the other picture you can clearly see small patches of toxic algae (the dark brown/black patches) amongst large patches of diatom growth.

It’s safe to use the river, but please remain cautious if you are taking your dog down there and make sure they don’t eat anything suspicious (even a small amount of toxic algae can be lethal if they eat it).

On the western side of the region, there is a water quality warning in place for Porirua Harbour at the Rowing Club. The latest sample recorded high bacterial counts which means the site is currently unsafe for swimming. This may have been due to recent rain in the area – rainfall flushes contaminants from land into waterways and we advise you not to swim for at least two days after rainfall, even if a site generally has good water quality.

Don't forget to keep up-to-date with the latest water quality warnings by visiting our interactive water quality map at bit.ly...