Health warning removed for Waiau River at the Waiau township

Friday August 3, 2012

​The Community and Public Health division of the Canterbury District Health Board has lifted its health warning issued in February this year for the Waiau River.

Recent surveys at the Waiau River site have shown the quantity of potentially toxic blue-green algae (benthic cyanobacteria) in the river has decreased to below levels harmful to public health.

Dr Alistair Humphrey, Canterbury Medical Officer of Health, says Environment Canterbury's sampling of popular swimming spots will resume in the summer.

"The public will be informed if testing shows concentrations have increased and there is a risk to public health again," Dr Humphrey says.

Facts about cyanobacteria:

  • Appears as dark brown/black mats attached to rocks along the riverbed
  • The algae occur naturally but can increase rapidly during warmer months
  • It often has a strong musty smell and algal toxin concentrations can vary over short periods with changing environmental conditions
  • Although high river levels will remove the algal bloom, detached mats can accumulate along the shore and increase the risk of exposure to toxins
  • If a health warning is in place avoid contact with the water
  • Although district or city councils may place warning signs, these may not be seen at the numerous river access points, hence the need for people/ dog-walkers to treat every low-flowing river cautiously.

For further information visit http://ecan.govt.nz/services/online-services/monitoring/swimming-water-quality/Pages/river-warnings.aspx

Or contact Community and Public Health on (03) 364 1777.

Page last reviewed: 17 July 2013
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