Waikato River test results too late to be useful

By ELIZABETH BINNING and GREGG WYCHERLEY

Test results expected today might be too outdated to determine whether a bloom of algae in the Waikato River is toxic.

Health warnings were issued last week advising people to stay away from the river because the algae were considered potentially toxic and the water possibly harmful to humans.

Samples were sent to laboratories in Wellington to determine if the algae were toxic, but the results were not expected back until today.

However, Environment Waikato water quality expert Bill Vant said those tests might be too outdated to tell if the water is dangerous to humans. "There's always the possibility that the algae could change."

Mr Vant said algae that were not toxic last week could develop to a stage where they were now releasing toxic byproducts into the water.

If the algae have developed to that stage the pending test results would no longer be accurate when they arrive.

New tests would have to be taken and sent away. It could then take several days until the new results were available.

In the meantime, local authorities and health officials are standing by the health warning, which advised people between Taupo's Orakei-Korako and Port Waikato to avoid contact with the river.

Contact with toxic water could cause skin irritations, asthma and problems with the liver and nervous system.

Treated drinking water is safe for human consumption.

Mr Vant said other tests taken last week found higher than normal concentrations of algae all along the river. In some places the counts were more than double the safe limit for human contact.

By Friday those counts had reduced - in some parts to safe levels - following heavy rain the previous night.

However Mr Vant said it was unlikely the downward trend would remain and he predicted tests taken today would show a rise in algae growth again.

This is because algae in the river were diluted by heavy flood water on Thursday night. Once that water receded algae from the hydro dams were likely to flow back into the river in high concentrations.

Medical officer of health Felicity Dumble said the health warnings would remain in place, regardless of what the first toxicity tests showed.

It will take three consecutive tests with non-toxic results and low concentrations of algae before the river would be declared safe again for recreational users.

While Dr Dumble recommended people follow the health warnings she said the fact no one had reported any illnesses after having contact with the river, was a good sign.

Marathon swimmer Paul Percy has been swimming the length of the Waikato River to raise diabetes awareness. He arrived in Hamilton on Saturday afternoon, escorted by a Tainui waka and greeted by a small but enthusiastic crowd on the riverbank.

He said he had been drinking the river water as he swam, and had noticed no health problems from pollution or toxic algae.

"I haven't grown any gills or extra fingers or anything."


Herald feature: Environment