Debris balls found on Sydney and South Coast beaches over recent months likely originated from Sydney Water’s land-based sewage treatment network, according to NSW Environment Protection Authority.
The development follows scientific and technical investigations that found similarities between the make-up of the debris balls and samples taken from several of Sydney Water’s major waste-water treatment plants, including those at Malabar and Bondi.
Adam Gilligan, Director Operations for NSW EPA said the EPA has issued an investigation notice to Sydney Water to pinpoint the precise source or sources of the debris balls within its network.
“This is a significant step forward in our investigation but there is still work to do,” said Gilligan.
“While we are yet to determine exactly what caused the pollution incidents to occur when they did, we can say the composition and the characteristics of the debris balls are consistent with a land-based sewage source.”
As part of ongoing investigations, NSW EPA has established a Wastewater Expert Panel to provide independent scientific advice to the EPA and other New South Wales Government agencies
The debris balls first appeared on eastern suburbs beaches in New South Wales on October 2024.
EPA’s investigation into the origin of the debris balls expanded earlier this year after additional pollution events on the South Coast and Northern Beaches.
Several of Sydney’s wastewater treatment plants and visiting cruise ships were sampled for comparison.
The EPA’s Investigation Notice will require Sydney Water to undertake oceanographic modelling of the dispersion of the debris balls, complete a sampling and analysis program at its sewage treatment plants and assess its deep ocean outfall systems and its sewerage pipe network to identify where in its systems the debris balls originated to prevent a recurrence.
NSW EPA has completed extensive chemical analysis of the balls and in late 2024 shared test results identifying that the debris contained fatty acids and petroleum hydrocarbons, as well as organic and inorganic materials.
For more information, visit: www.epa.nsw.gov.au/
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