The Tukituki River Photo: RNZ / Cole Eastham-Farrelly
Swimmers and dog owners in Hawke's Bay are being urged to beware of toxic algae in the Tukituki River.
Toxic algae has also been widespread throughout the East Coast this summer, prompting warnings against collecting shellfish.
Multiple blooms have been identified near Walker Road in Central Hawke's Bay, which is now listed as unsuitable for swimming on the Land Air Water Aotearoa (LAWA) website.
"We've had a spell of long, hot days in Hawke's Bay - river levels are dropping, and water is moving slowly, creating the perfect environment for algal growth," said the council's water quality and ecology monitoring team lead Jordan Ellmers.
It posed health risks for people and dogs if it was touched or ingested, he said.
People should look out for mats which could vary in colour from brown or black in the water, to a pale brown or whitish colour when dry.
"Toxic algae can emit a musky smell that's particularly appealing to dogs. Once they've had a sniff, it can be hard to stop them from licking or eating it," Ellmers said.
People were also encouraged to keep an eye on kids paddling in the shallows where toxic algae had begun to appear, he said.
Toxic algae on a rock at river's edge. Photo: Supplied / Greater Wellington Regional Council
The council's environmental monitoring team is testing weekly at sites along the Tukituki, Tūtaekurī and Esk rivers.
But it was not possible to survey the entire length of each river, Ellmers said.
"People need to be aware of the risks at their swimming spot and take precautions when visiting.
"Toxic algae can detach from rocks and drift downstream to different parts of the riverbed, so always check the water before you take a dip."
Te Whatu Ora Medical Officer of Health Dr Bridget Wilson said anyone who got sick after being in a riverbed should seek medical advice urgently.
Swallowing water containing toxic algae could cause serious illness with symptoms including vomiting, diarrhoea, and skin rashes, she said.
Any animals that seem unwell after being at the river should be seen immediately by a vet.
