Mystery surrounds 'bright blue' canal in Sydney

Residents in Sydney have been left baffled after spotting a stream of brightly coloured water running through Alexandra Canal.

The bright blue colour was seen on December 18 in the heritage listed canal that runs through the inner city suburbs of Alexandria, Mascot and St Peters before flowing into the Cooks River.

Tagging the City Of Sydney, resident James Fletcher posted vision of the canal to Twitter, showing the coloured water.

The  Alexandra Canal with bright blue water running through it.
'I can’t imagine it’s good for the diverse wildlife': Sydney residents were concerned when water in the Alexandra Canal turned 'bright blue'. Source: Twitter

“Just wondering why Alexandria Canal [sic] is running bright blue? I can’t imagine it’s good for the diverse wildlife that frequents the waterway,” Mr Fletcher wrote.

“Any clues to why and who?” Mr Fletcher added, this time tagging The NSW Environment Protection Authority.

The City Of Sydney referred Mr Fletcher to Sydney Water and suggested he may be able to find some answers there.

Twitter users were curious as to what could have caused such a bright colour in the water, with many replying with their concerns.

“They don't give a rats about the environment. Teflon attitude is strong in this tweet!” one person replied.

“Was there an answer to this? Surely big concern!” another user wrote.

Sydney Water told Yahoo News Australia they are “investigating the source of a potential contamination” in the canal.

“Network technicians have been deployed to trace the source of the discolouration after being alerted to the issue by local residents,” a spokesperson said.

“Sydney Water will focus on a large stormwater network and nearby area to try and identify the cause.”

Earlier this year a creek in Melbourne’s north turned bright pink with the EPA investigating the strange discolouration.

Meanwhile in Queensland a naturally occurring plankton bloom had locals comparing the water to “fairy floss”.

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