People have been advised to stay away from the Kahutara River, near Kaikoura, after it tested positive for potentially toxic algae.
The mouth of the river at Peketa, seven kilometres south of Kaikoura, has been blocked for most of the whitebait season, and a large discoloured lagoon has formed.
The community and Public Health division of the Canterbury District Health Board issued a health warning after potentially toxic blue-green algae (benthic cyanobacteria) was found.
Canterbury Medical Officer of Health Alistair Humphrey said people and animals should avoid the river, near State Highway 1, and the lagoon.
A Kaikoura fisherman said it was first time he had seen the river that bad in 55 years.
He blamed slip material just above the State Highway 1 bridge at Peketa.
Kaikoura whitebaiters believed the increase in material in the river had caused the ‘lagooning’, and not allowed the river to flow normally. The algae extends from the main stem of the river down into the lagoon south of the Peketa camping ground.
“The mats are detaching and will be accumulating in the lagoon, so I would advise that the lagoon be avoided,” Humphrey said.
“The benthic mats may also extend further upstream and river users should keep an eye out for dark brown or black mats which can produce toxins harmful to people and animals.”
Exposure could cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips, Humphrey said.
“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.”
Boiling the water from the river did not remove the toxin and therefore should not be consumed, Humphrey said. Affected animals should be taken to a vet.
Environment Canterbury was monitoring the sites and the public would be advised of any changes in water quality, Humphrey said.
View original article at: Warning as potentially toxic algae fills river