Locals shocked to see Sydney harbor water turned blood red

Residents of Sydney have been left puzzled and concerned after discovering mysterious red water flowing into the sea at Careening Cove, a bay that runs into Sydney Harbour. According to the Mirror, footage captured at the scene shows the water turning a bright red, with foaming red waves lapping around the base of a wooden pier. The striking discoloration prompted a quick response from local and regional officials.

Locals spotted the red stream flowing through the wealthy suburb of Kirribilli, particularly near Milson Park, where the tainted water reached homes and boats, reported The Sun. The unusual event left the local population, who walk along the coast daily, perplexed. Experts were also baffled and requested assistance from local authorities, as mentioned in Semana.

Curious onlookers traced the vivid color back to a stormwater drain, but neither the North Sydney Council nor the New South Wales Environmental Protection Authority (EPA) could identify the source of the dramatic red color, according to the Mirror. The mystery deepened when officers from the North Sydney Council were sent to investigate, with the NSW EPA also becoming involved, as reported by The Sun.

A spokesperson for the North Sydney Council stated, "The council is aware of the presence of red water flowing into the harbour from Milson Park, and agents have investigated, but they have not been able to find the source," according to Semana. Both local and regional authorities were sent to investigate the red water but have not yet concluded its source.

Authorities have proposed only one theory regarding the cause of the color change. They suspect that the ruby red hue in the water is likely caused by hydraulic dye, also known as fluorescein, which plumbers use to detect leaks in drains or pipes, as per the Mirror. 

The NSW EPA stated that fluorescein is not a toxic substance but can create dramatic colors. "Fluorescein has low toxicity but even small amounts can be highly visual and for this reason its use should always be minimised," the NSW EPA noted, according to The Sun.

This is not the first time Australians have been startled by bright red shores. In 2012, several Australian beaches turned red due to thick blooms of algae called Noctiluca scintillans, also known as "red tide" or "fire in the sea." These algae washed up on several stretches of sand near Sydney, including Bondi Beach, as reported by The Sun.

This article was written in collaboration with generative AI company Alchemiq