Hutt Valley rivers safe to swim in as rain flushes out toxic algae

Screenshots of video taken by the Greater Wellington Regional Council show toxic algae as the dark sections of the Hutt River. Photo / Supplied

Rivers in the Hutt Valley area are now safe to swim in after recent rain flushed out the toxic algae that could have been fatal to humans and pets.

The Greater Wellington Regional Council has given the all-clear for people to swim in the Hutt River/Te Awakairangi following an assessment of the water today.

"The heavy rainfall over the weekend resulted in seven times the median flow, enough to flush the river, and our latest assessment confirm that the significant growth found before Christmas has for the most part disappeared," said Greater Wellington environmental scientist Dr Mark Heath.

"People can now swim and walk their dogs in the confidence that the river's water no longer presents any danger from swallowing toxic algae.

"Given the dry summer, however, it is possible that toxic algae may recur, so we urge people to check before they swim by visiting Greater Wellington's website and reviewing the interactive maps that show the condition of our river, lake and coastal waters."

Signs warning of toxic algae will be removed over the next 24 hours.

Late last year the warning was put out that the waterways were unsafe to swim in, with the risk of toxic algae mats being swallowed by swimmers.

Such an occurrence could potentially have been fatal, Greater Wellington said at the time.

The Greater Wellington Regional Council monitors water quality on a weekly basis throughout summer and posts water ratings on the Is it Safe to Swim? pages of its website.