The Waikirikiri-Selwyn River. Photo: Green Ideas editor Greg Roughan
Canterbury health officials are warning people to avoid the Waikirikiri-Selwyn River at Glentunnel because of a potentially toxic algae.
Benthic cyanobacteria - which looks like dark brown or black mats attached to rocks - can be harmful to people and animals, Te Whatu Ora Waitaha Canterbury said on Wednesday afternoon.
"Exposure may cause skin rashes, nausea, stomach cramps, tingling, and numbness around the mouth and fingertips," Dr Cheryl Brunton, medical officer of health, said.
Te Whatu Ora says the algae can cause rashes, nausea, stomach cramps, tingling, and numbness around the mouth and fingers.
"If you experience any of these symptoms, visit your doctor immediately," Brunton said.
The algae had a "strong musty smell", the result of "a combination of available nutrients in the water and sediments (such as nitrogen and phosphorus), a sustained period of low and stable flows, and favourable weather conditions", such as warm, still days.
Pets that come into contact with benthic cyanobacteria should be taken to the vet immediately, should they show signs of illness.
"There are also other access points along the Waikirikiri-Selwyn River at Glentunnel that may have benthic cyanobacteria present," Te Whatu Ora said.
The algae has appeared in previous years, prompting warnings.
