Residents in Sydney's affluent Kirribilli neighbourhood were stunned on Wednesday after a bright green substance was seen leaking into Careening Cove at Milson Park, near the prime minister's official residence. The vivid colouring, described by one local as resembling 'green cordial' and 'the radioactive stuff you see in superhero movies', prompted a response from Fire and Rescue NSW.
Superintendent Adam Dewberry confirmed the substance was non-toxic and likely fluorescein dye, commonly used as a flow tracer. He compared the incident to the annual St Patrick's Day dyeing of the Chicago River, but noted this was unplanned. The dye entered the harbour through a storm water drain, with Dewberry saying the source was difficult to trace due to numerous access points in the area.
Professor Stuart Khan, an environmental engineering expert from the University of Sydney, said the amount of dye used was excessive—'probably a whole bucket full'—far exceeding the typical teaspoon used for legitimate purposes. He concluded the dye had been misused, either as a prank, possibly linked to year 12 'muck-up day', or through poor practice.
North Sydney Council deployed spill socks to prevent further pollution, and by Wednesday evening the drainage network was clear. Overnight rain helped flush and dilute the dye, and by Thursday morning the bay had returned to normal. Dewberry noted no evidence of marine damage, fish kills, or staining on boats or shorelines. Sydney Water confirmed it had not used the dye in the area.
