A member of the public alerted the Otago Daily Times to a large area of green water near the Vauxhall Yacht Club on the Otago Peninsula on Friday.
He believed the area of fluid was about 80m long and 20m wide.
‘‘I [phoned] the Otago Regional Council and let them know about it. It looked sort of like a glycol, like florescent green. It could be a tracer dye.''
ORC director of environmental monitoring and operations Scott MacLean said three calls to the pollution hotline and a subsequent investigation found the fluid to be a green tracer dye commonly used for finding things like leaks in pipes.
The Dunedin City Council was testing the pipe under consent, Mr MacLean said.
‘‘I believe it's used for those sorts of things, looking for leaks. That's what it's generally used for. I guess it allows them to put it in one end and follow it out.''
Mr MacLean reassured the public that using tracer dye was a fairly common practice and was harmless.
DCC group manager water and waste Laura McElhone said a homeowner was experiencing ‘‘seepage'' on their property and contacted the DCC.
The seepage control unit was sent in to test mud tanks and would have checked the stormwater pipe as a precaution, Ms McElhone said.
The dye was a plant-based, non-toxic substance. People were encouraged to call the pollution hotline on 0800-800-033 if they suspected contaminants in the water.
