Monitoring has identified relatively large amounts of a potentially toxic planktonic (free floating) cyanobacteria in Saltwater Creek at Coonoor Road. Community and Public Health have therefore issued a health warning and signage will be erected at that site. Once monitoring indicates that the river is safe, the signs will be removed.
Opihi River at SH1
Humans and animals, particularly dogs, should avoid these areas until the health warning has been lifted.
Canterbury Medical Officer of Health Dr Daniel Williams says the algal mats can produce toxins harmful to humans and animals.
"Exposure may cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips," Dr Williams 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."
"No one should drink the water from the river at any time", as boiling the water from the river does not remove the toxin.
Animals should be taken to a vet immediately if they come into contact with the contaminated rivers.
Environment Canterbury is monitoring the sites and the public will be advised of any changes.
Facts about planktonic cyanobacteria:
Planktonic cyanobacteria are algae that are suspended in the water column of slow moving waters such as a lake or lagoon
They are not generally visible with the naked eye, but the water column may appear discoloured or cloudy
The algae occur naturally but can increase in concentration rapidly during warmer months.
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 low-flowing rivers and lakes cautiously.
Further information on cyanobacteria is available from ECAN:
For more information on health effects, contact Community and Public Health on (03) 687 2600.
Health Alerts Archive
For a full list of the convenient ways that you can contact us, refer to the Contact Us page
Connect With Us