December 4, 2015
Health Warning – Algal Bloom in Selwyn/Waikirikiri River at the Whitecliffs Domain
The Community and Public Health division of the Canterbury District Health Board have issued a health warning after
potentially toxic blue-green algae (benthic cyanobacteria) were found in Selwyn/Waikirikiri River at the Whitecliffs
Domain.
People and animals, particularly dogs, should avoid the area of the Selwyn River at Whitecliffs Domain until the health
warning has been lifted.
Dr Alistair Humphrey, Canterbury Medical Officer of Health, says the algae look like dark brown to black mats and can
produce toxins harmful to people and animals.
“Exposure may cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips,” Dr
Humphrey says.
“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.”
The Selwyn District Council as the drinking water supplier are following agreed procedures to ensure their reticulated
drinking water supplies are safe.
“No-one should drink the water from the river at any time, even after boiling the water from the river, it does not
remove the toxin therefore should not be consumed,” Dr Humphrey says.
People and animals should remain out of the waterways until the warnings have been lifted.
“Pets should be taken to a vet immediately if they are showing signs of illness after coming into contact with algal
mats.”
Environment Canterbury is monitoring the sites and the public will be advised of any changes in water quality, 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 Environment Canterbury’s website
Or contact Community and Public Health on (03) 364 1777.
ENDS