Sydney residents are left baffled after a mysterious substance turned parts of the harbour fluorescent green.
Residents of Kirribilli, near Milsons Park, were stunned when they saw the water in the bay along Hipwood Street turn bright green at around 3pm on Wednesday.
Concerned residents immediately called the fire department to investigate the unusual sighting.
Firefighters said they were alerted to a “large spill of fluorescent green material flowing into the harbour”.
The mysterious green substance was first noticed around 12:00 noon, when it flowed from a storm drain into the harbor.
A local resident described the water as “green liquor” and told 9News it looked like “the radioactive stuff you see in superhero movies.”
Authorities tested the water and found that the green substance was non-toxic and did not harm the environment.
NSW Fire and Rescue said the source of the leak was still “unclear” but said the leak was likely coming from a stormwater drain.
The water in the bay along Hipwood Street in Kirribilli, near Milsons Park, turned fluorescent green
Authorities said the source of the leak was “unclear” but said it appeared to be coming from a storm drain
However, social media users claim to have solved the mystery, with many claiming the cause is a discharge dye called fluorescein.
Fluorescein is a non-toxic contrast agent used by plumbers to detect leaks, trace the location of pipes, and detect damage to drains and waterways.
“It’s drain paint. Plumbers use it to trace where drains lead. It’s completely harmless. I suspect the student used too much,” one person wrote.
“A Sydney water engineer dropped the bucket of plumber’s paint and didn’t tell anyone,” a second person said.
“It was the student who threw the bucket of paint into the rainwater pipe,” said a third.
Others suggested that the plumber’s paint was used as part of ‘muck-up day’, an Australian tradition among school leavers where final year students organise fun activities or play pranks during their last week at school.
Authorities are working to flush the substance from the harbor and believe rain on Thursday could return water levels to normal.