Health Warning – Toxic Algal Bloom in Selwyn/Waikirikiri River at the Whitecliffs Domain
Canterbury District Health Board’s Community and Public Health unit has issued a health warning after potentially toxic
blue-green algae (benthic cyanobacteria) were found in Selwyn/Waikirikiri River at the Whitecliffs Domain. This warning
is in addition to the media release for the Selwyn/Waikirikiri River at the Whitecliffs picnic area (downstream of the
Whitecliffs Domain) which was issued on 21 January 2020.
People and animals, particularly dogs, should avoid the area of the Selwyn/Waikirikiri River at the Whitecliffs Domain
until the health warning has been lifted.
There are also other access points along the Selwyn/Waikirikiri River that may have cyanobacteria present and people are
advised to check for the presence of cyanobacteria and avoid contact.
Dr Ramon Pink, Canterbury Medical Officer of Health, says some of the cyanobacterial mats are accumulating along the
river edge and are bright green in addition to the usual brown/black colour. They can produce toxins harmful to people
and animals.
“Exposure may cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips.
“If you experience any of these symptoms, visit your doctor immediately, also let your doctor know if you’ve had contact
with dark brown/black algal mats or water in this area,” says Dr Pink.
The Selwyn District Council as the drinking water supplier are following agreed procedures and monitoring their nearby
drinking water intakes.
“No-one should drink the water from the river at any time, even after boiling the water as it does not remove the toxin
therefore should not be consumed,” Dr Pink says.
Pets should be taken to a vet immediately if they are showing signs of illness after coming into contact with algal
mats.
People and animals should remain out of the waterways until the warnings have been lifted.
Environment Canterbury is monitoring the sites and the public will be advised of any changes in water quality.
Facts about cyanobacteria:
• The algae occur naturally but can increase rapidly during warmer months.
• Algal blooms are caused by a combination of nutrients in the water (such as nitrogen and phosphorus), and
favourable weather conditions (e.g. increased temperature, calm days).
• If the water is cloudy, discoloured, or has small globules suspended in it, avoid all contact.
• Not all cyanobacterial blooms are visible to the naked eye and toxins can persist after the blooms disappear.
• Cyanobacterial concentrations can change quickly with changing environmental conditions (e.g. wind). If a health
warning is in place avoid contact with the water.
For further details visit: https://www.lawa.org.nz/explore-data/canterbury-region/
Or contact Community and Public Health on (03) 364 1777:
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