EPA south-west region manager Carolyn Francis said a thorough investigation was still underway and would take some time to complete, however, she said a field investigation last week backed up community reports about how the nurdles got onto the beaches.

Nurdles are a type of plastic used in manufacturing, and water corporation Wannon Water has said they made it through the Warrnambool Sewage Treatment Plant.

“EPA and Wannon Water are working to establish the original source of the nurdles, how they were able to get through the treatment plant and what needs to happen to clean up the impacted beaches,” Ms Francis said.

“EPA will be using remedial notices to formalise those management and clean-up requirements.”

Ms Francis said the EPA was still investigating whether there were breaches at both the Wannon Water treatment plant and the original source of the nurdles.

The EPA has said Wannon Water could face hefty fines if it was found to have breached its licence to release treated water into the ocean.

Last week Wannon Water’s service delivery manager Ian Bail said the licence it operates the plant under included the prevention of discharge of plastics.

Environment Minister Lily D’Ambrosio has also weighed into the issue, describing it as an “unfortunate incident”.

“I want to thank every local who has given up their time to help with the clean-up,” she said.

“We want to prevent incidents like this from occurring in the first place by encouraging everyone to think about how they dispose of their waste and the potential impact on the environment.”

The minister said her government was taking action, such as banning lightweight plastic shopping bags, to reduce the likelihood of waste entering the environment.

Volunteers leading the nurdle clean-up reported on the  Wednesday that the plastic pieces had been found at all beaches in Warrnambool and Port Fairy, and also in areas including Yambuk.

Environment activist group Sea Shepherd has organised an emergency clean-up event for this Sunday from 2pm to 4pm.