Leaking oil containers, fridges, a spa and a shipping container are among the debris floating down the Hawkesbury River and turning up on beaches in Sydney's north.
While the flooding rain has eased in Sydney's west, residents of places such as Dangar Island are discovering material that has travelled potentially more than 100 kilometres down the river.
Beaches on the island are becoming coated with piles of mostly wooden debris riddled with plastics and styrofoam, with the occasional large item.
A 1,000-litre container that washed up on Dangar Island leaked hydraulic oil near a protected reef.
Hazmat crews from New South Wales Fire and Rescue were called to the scene to isolate the leaking oil container.
Fortunately, members of the community were able to right the container before firefighters arrived.
Environmental group Clean4Shore founder Graham 'Jono' Johnston said chemicals travelling down the river in containers were one of the main concerns for communities in the wake of the floods.
"They [residents upriver] are storing chemicals on flood-prone land, and this flood has picked the chemicals and the drums up and just put them back in the river again," Mr Johnston said.
Island locals regularly have material wash up in the wake of major floods.
President of the Dangar Island community association, Stephen Boyle, said he was concerned about homes built on the flood plain further up the river.
"We're seeing the results of people's destroyed homes," Mr Boyle said.
A Hornsby Council spokesperson said they were aware of large debris in the water around Dangar Island and in Parsley Bay at Brooklyn, and were in contact with state agencies to resolve the issue.
Ferry services disrupted
Logs and debris protruding from under the wharf on Dangar Island forced the island's ferry service to be suspended all day on Wednesday.
Ferry operator Richard Stockley described the southern beach of the island as "utter carnage".
While services were able to resume the following day after locals were able to remove the obstructing logs, the debris floating down the river meant the journey was still too hazardous to perform at night.
"Once it becomes dark, you know, we don't have streetlights or flood lights on the water like a road," Mr Stockley said.
While Mr Stockley appreciated the efforts to clean-up non-organic debris, he said not enough was being done to remove organic debris such as logs which threaten boats on the river.
"The logs and the things that can sink vessels or kill people if they get run into at night, they get left behind just to float off on the next tide," Mr Stockley said.
"The danger from debris continues on for a far longer period after the actual flood event."
Thousands of cubic metres already cleaned up this year
The New South Wales Environment Protection Authority (EPA) has not yet commenced the clean-up of the Hawkesbury following the recent event, citing the current dangerous water conditions.
However, the EPA said they have already collected more than 6,000 cubic meters from the Hawkesbury River and Central Coast waterways this year.
This accounts for the lion's share of the almost 9,000 cubic metres removed across the state since late February.
Residents in flood-affected areas are warned by the EPA to steer clear of beaches and waterways due to the impact the floods have had on water quality.
Central Coast beaches bracing for impact
Mr Johnston, from Clean4Shore, said the debris was a major risk to people in the area using the waters for boating, but also for surfing, which is typically done at beaches further from the Brooklyn area.
Waste was being reported in communities as far away as MacMasters Beach on the Central Coast. Two water tanks and five car tyres were among the debris found on the beach on Thursday.
"I expect more Central Coast beaches to feel the effects of the debris that's washing out past Patonga into the ocean, and then the wind and swell putting it all back on the beaches," Mr Johnston said.
