People are being warned to be careful around streams and rivers as dropping water levels and temperature rises could see toxic algae return this summer.
Last summer, the toxic algae phormidium was discovered in the Silver Stream at Mosgiel and was thought to have contributed to the death of at least one dog.
As a result, the Otago Regional Council put up warning signs along the popular Silver Stream walkway and warned people with dogs to stay out of the waterway.
Council environmental infor- mation and science director John Threlfall said last year it was confirmed the algae was growing upstream in the Silver Stream and coming down in clumps.
It was expected the algae would make a reappearance this year, as temperatures warmed up and flows dropped.
The council would be making regular checks and had already detected the algae's presence in a publicly inaccessible area of the Shag River, where it had also been found last year, he said.
"The general advice is that people should be aware that blue-green algae can be in any Otago river."
If the algae was found to be in the Silver Stream, the council would look at putting up signs warning people of its presence and to keep their dogs out of the water, Dr Threlfall said.
