An Australian-first assessment of microplastic pollution has identified the state’s most contaminated coastal waterways, with the Cooks River, Dee Why Lagoon, Muddy Creek and the upper Parramatta River topping the list.
The study, known as the Broadscale Microplastic Assessment, was delivered by the NSW Environment Protection Authority in partnership with the NSW Department of Climate Change, Energy, the Environment and Water. The three-year project analysed microplastic concentrations in the top 15 centimetres of surface water across coastal waterways throughout New South Wales.
Sampling was carried out across 120 catchments stretching from the Tweed River in the north to the Victorian border. The results rank waterways from most to least contaminated and provide authorities with new insights into how microplastics move through the environment.
EPA Chief Executive Tony Chappel said the findings would guide future work to better understand and address plastic pollution.
“Microplastics are one of the fastest-emerging threats to marine life and our environment, often washed from land into rivers and then into the ocean through stormwater drains,” he said.
“For the first time, we’ve sampled 120 catchments from the Tweed to the Victorian border to identify the most affected sites, the types of microplastics present, and where we can make the greatest impact.”
Microplastics were detected in every waterway sampled, highlighting the widespread nature of plastic contamination across urban, regional and remote catchments.
The study identified the state’s top ten microplastic hotspots as the Cooks River, Dee Why Lagoon, Muddy Creek, Toongabbie Creek in the upper Parramatta River, Throsby Creek, Coffs Creek, South West Rocks Creek, Manly Lagoon, the Parramatta River and Middle Harbour Creek.
In contrast, the least contaminated waterways were Myall Lake, Nadgee Lake, Middle Lagoon, Myall Broadwater and Wallaga Lake. Each of these locations sits within minimally disturbed catchments along the state’s north and south coasts.
Across the study, researchers identified more than 31,000 plastic particles. Among them were foam packaging fragments and plastic pellets known as nurdles. These materials are considered priority microplastics because their sources can potentially be traced and controlled.
Chappel said the assessment would help translate scientific findings into practical action.
“Putting microplastics under the microscope gives us a clear indication on where targeting our efforts is needed,” he said.
The EPA plans to use the dataset to develop models that map pollution sources and pathways. This work aims to better target preventable pollution, support collaboration with water managers on local solutions and strengthen policies designed to keep microplastics out of waterways and ecosystems.
As part of this effort, the EPA will map how litter travels through the Cooks River and Manly Lagoon, tracing plastic from streets to the sea to identify where intervention will have the greatest impact.
New South Wales is also pursuing other measures to reduce plastic pollution, including increased compliance on plastic bans, community awareness campaigns and litter prevention grants.