Documents reveal one of Australia's biggest oil and gas companies knowingly shed plastic into the ocean for two months before notifying the offshore regulator.

Earlier this year, almost 200 kilograms of plastic waste washed up on Victorian shores during decommissioning works at a gas well and oil pipeline owned by energy giant Woodside.

The company has been investigated by the National Offshore Petroleum Safety and Environment Management Authority (NOPSEMA).

The investigation found Woodside breached its environmental obligations by continuing the operation despite knowing the environmental risks.

Environmental experts are warning Australia is headed for a "decommissioning nightmare" unless the offshore regulator cracks down on how companies handle oil and gas facilities at the assets' end of life.

The timeline

Woodside engaged company Subsea 7 to undertake decommissioning works, which began in January 2025, at the Minerva gas well and pipeline off the coast of Port Campbell in south-west Victoria.

The Minerva wells are located in the ocean approximately 11 kilometres off the coast of Port Campbell in Victoria's south-west. (Supplied: Woodside Energy)

Subsea 7 filed an incident report with Woodside on January 12 after a component of a plastic saddle clamp was dislodged and lost in the ocean.

The report noted the risk of further saddle clamp losses into the sea was likely.

In February 2025, volunteer beach clean-up crews began discovering large chunks of plastic near Warrnambool, more than 60 kilometres from the pipeline.

Components of plastic saddle clamps were found washed up on Victorian shores. (Supplied: Colleen Hughson)

Some of the plastic pieces collected from Victorian beaches. (Supplied: Colleen Hughson)

Woodside launched an investigation into the matter on March 8, 2025, almost two months after the first saddle clamp was lost in the ocean.

Over the next two days, an estimated 29 plastic saddle clamp components were released into the sea.

Woodside said it notified NOPSEMA of the plastic pollution on April 15, 2025, via submission of its "monthly recordable environmental incident notification report".