Surfdale Beach on Waiheke Island is one of the beaches to avoid. Photo: Waiheke Local
Aucklanders are being warned to avoid black algae on three Waiheke beaches, ahead of a clean-up operation.
It comes after more testing on the algae at Surfdale, Blackpool and Shelly beaches identified the presence of the toxin lyngbyatoxin-A.
It can cause skin or eye irritation if in contact with the water.
Auckland Council is telling people not to swim, wade or touch the seaweed or algal material from the affected beaches.
It will soon remove the algae from all three beaches.
Council's director or infrastructure and environmental services Barry Potter said advice was being sought for the best way to remove the algae "swiftly and safely".
"Until the algae has been cleared, our advice to residents and visitors is to steer clear of the affected areas, and to visit other Waiheke beaches for swimming and recreation."
Te Whatu Ora northern region medical officer Dr David Sinclair said people should not swim, wade or touch the seaweed or algae.
"If you feel unwell as a result of contact with the bloom, you should contact your doctor, or call Healthline on 0800 611 116."