Waikato swim ban as algal bloom spreads

By ELIZABETH BINNING

New Zealand's longest river, the Waikato, has been closed to swimmers because of a potentially toxic algal bloom in the water.

Health officials yesterday issued a warning against all contact with the water of the Waikato River, including drinking untreated water.

The advice extends to rowers and jet-skiers.

The warning came after a meeting of water experts, health officials and representatives from the Waikato councils heard that the algal infestation had reached more than twice the safe limit for human contact in some places.

Scientists are trying to determine whether the naturally occurring algae, which have spread rapidly, are toxic.

Signs warning against swimming will go up today along the 425km river from Orakei-Korako, at Taupo, to Port Waikato.

Effluent from farmland, treated waste from industries and sewage from several plants enter the river along its path.

Councils have rushed to reassure residents that treated drinking water drawn from the Waikato is safe.

For days residents have been complaining about a musty taste and foul smell from tap water caused by the algal bloom.

The blue-green bloom, spreading rapidly in the hot, humid weather, has been identified as Anabaena planktonica, but it is too early to know if it is a toxic variety.

Results of toxicity tests, sent to laboratories at the Institute of Environmental and Scientific Research and Massey University in Wellington, will not be available until Monday at the earliest.

Waikato medical officer of health Felicity Dumble issued the warning late yesterday afternoon. "At this stage all we can be certain of is that blue-green algae levels are high."

If the algae are toxic and people come into contact with the water they could experience breathing difficulties, skin irritations, or problems with their livers and nervous systems.

Taking water and boiling it for drinking is also inadvisable.

But diabetes fundraiser Paul Percy says that after 12 days swimming down the Waikato he has had no problems from the algae.

Mr Percy, 45, has also been drinking the water. "I've had no ill effects and our team is just going to play it by ear and see if things happen. If something happens, I'll pull out. If not, we carry on."

But Mr Percy advises people to take heed of the health warning.

"I spend so much time in rivers and waterways ... I've pretty much got immune to water bacteria."

About 10 per cent of Auckland's water supply is being drawn from the river at Tuakau. Watercare Services said yesterday it would continue to draw water from the Waikato.

Herald feature: Environment