Media release – Cyanobacteria found in two Southland rivers
For immediate use
Monitoring carried out by Environment Southland has shown high abundance of benthic cyanobacteria (blue-green algae) at
two sites in Southland.
People and animals, in particular dogs, should avoid contact with reaches of the Hamilton Burn around Affleck Road and
the Upukerora River around the Te Anau Milford Road until health warnings are removed.
Public Health South medical officer of health Dr Derek Bell says cyanobacteria produce toxins that are harmful to people
and animals if swallowed or through contact with skin. Boiling water does not remove toxins and drinking of the water
should be avoided at all times.
“Exposure to cyanobacteria may cause symptoms such as skin rashes, nausea, tummy upset and tingling and numbness around
the mouth or tips of fingers,” he says.
Cyanobacteria concentrations can vary quickly with changing environmental conditions. Environment Southland’s freshwater & marine science leader Nick Ward says cyanobacteria may be removed if river levels rise. “However, if the warm, calm
spell continues we could see more cyanobacteria developing in other rivers. It’s good to know what you’re looking for
and to keep your eyes peeled.”
Cyanobacteria occur naturally but can increase rapidly during warmer periods of the year. Benthic cyanobacteria usually
occur as dark brown/black mats which grow attached to rocks in the river or accumulate on the surface in shallow,
slow-flowing areas. They often have a strong, musty smell.
If you experience health symptoms after contact with contaminated water, visit a doctor immediately. Animals that
consume cyanobacteria should be taken to a vet immediately.
Environment Southland monitors cyanobacteria monthly at a number of sites across Southland and the public will be
advised of any changes in water quality that are of public health significance.
For further information, visit Environment Southland’s website www.es.govt.nz