Warnings of potentially toxic slime in Hurunui River and Lake Waihola
The Hurunui River at SH7 has high levels of toxic algae and people and animals should stay away.
The health warning from the Community and Public Health division of the Canterbury District Health Board (CDHB) follows the finding of high levels of the potentially toxic benthic cyanobacteria Phormidium in the Hurunui River.
The CDHB advised that no one should drink water from the river.
People and animals, particularly dogs, should avoid that area of the Hurunui River until the health warning has been lifted.
Phormidium mats have been found to be detaching and accumulating at the sides of the river, as well as floating towards the swimming hole located upstream of the SH7 bridge, behind the Balmoral camp ground.
The CDHB said the swimming hole should not be used until further notice.
Medical Officer of Health Dr Alistair Humphrey said the algae looked like dark brown or black mats and could produce toxins harmful to people and animals.
"Exposure may 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."
Pets that show signs of illness after coming into contact with algal mats should be taken to a vet immediately.
Humphrey said people and animals should remain out of the waterways until the warnings have been lifted.
Environment Canterbury was monitoring the site and the public would be advised of any changes in water quality.
Otago Regional Council also issued a warning about high concentrations of cyanobacteria found in Lake Waihola.
"Visitors are advised not to use it for recreational purposes and observe warning signs until the warning has been lifted," the council said in a press release.
Lake Waihola has a history of cyanobacteria problems, but the last time there was enough to prompt a council warning was three years ago.