The Northern Beaches has some of the highest levels of coastal waterway microplastic contamination in the state, a study has revealed, even rivalling those of major cities overseas.
Dee Why Lagoon was reported to have some of the worst contamination, sitting at number two on the top ten NSW microplastics hotspot list, just behind Cooks River in Sydney’s inner west, at number one.
The Australian first assessment, called the Broadscale Microplastic Assessment, was conducted from 2021 to 2024, sampling 120 catchments from the Tweed to the Victorian border. It was commissioned by the NSW Environmental Protection Agency (EPA) to determine which microplastics were present at each site and where the greatest impacts were.
Unfortunately for the Northern Beaches, three of its coastal waterways made the top ten most contaminated hotspots in the state. Manly Lagoon was placed at number eight, and Middle Harbour Creek – which runs through Davidson, Belrose and Frenchs Forest – came in at ten.
All three Northern Beaches locations had median values nearly four times the Grade E threshold.
Comparatively, Dee Why Lagoon’s median microplastic concentration exceeded the combined reported median concentrations of the River Seine, Paris, the Mediterranean Sea, Turkey, Dongshan Bay, China, and Tampa Bay, Florida – though direct comparisons are complex, as studies use different methodologies and particle size ranges.
Why Is Northern Beaches So Polluted?
To clarify, it’s not just that the Northern Beaches have a pollution problem; though urbanisation is part of the issue, the way the local lagoon systems operate also contributes.
Dee Why Lagoon is classified as a “back dune lagoon,” meaning a system with a very small catchment that is often closed off from the ocean for extended periods, sometimes years. During this time, microplastics are unable to be flushed out, and when they do, it’s often an accumulated influx.
Manly Lagoon’s system works similarly, but is classified as an intermittently closed system, as it is connected to the ocean more regularly.
But, as mentioned, the Northern Beaches is fighting a battle on two fronts as urbanisation makes the accumulation of plastic increasingly prominent. There is an increase of roughly 1 MP/m³ for every 10 per cent increase in urbanisation according to the Department of Climate Change, Energy, the Environment and Water’s (DCCEEW) report.
But microplastics contamination is not a Northern Beaches exclusive issue; out of all the coastal waterways sampled, only four received a ‘Grade A.’ Myall Lakes and Myall Broadwater in the Mid North Coast were deemed the cleanest and are remote, minimally disturbed coastal environments well away from urban development.
What Is The Source Of The Plastics
Urban areas generate microplastics through stormwater runoff, littering, drains, and synthetic surfaces like artificial turf, which then wash into waterways.
DCCEEW collected over 31,000 particles and categorised the samples into three size classes, with foam and fragments in the smaller classes and the largest number collected. Film, artificial turf and pellets were also recorded as priority microplastics because they can be traced and stopped at the source.
“We’ll do this by mapping how litter flows through the Cooks River and Manly Lagoon – tracing plastic from our streets to the sea so we can pinpoint sources.”
NSW EPA Chief Executive Tony Chappel says putting these particles under a microscope will give a clear indication of where to target preventable pollution.
“One way we’ll do this is by mapping how litter flows through the Cooks River and Manly Lagoon – tracing plastic from our streets to the sea so we can pinpoint sources and pathways, and direct action where it counts.”
Health Impacts On People And Pups
Studies have already shown that microplastics may contribute to adverse effects on human health, being linked to cardiovascular risk, cancer, and cellular damage. It’s unclear what the contamination in the surveyed areas on Northern Beaches could have on people.
However, Manly and Dee Why Lagoons’ water quality was categorised as “poor” by NSW Environment and Heritage Department, even before the knowledge of microplastics, so you may want to think twice before swimming or fishing in those areas. But as many locals already know, these waterways are also often a place for pets to play.
Right now, if you’re a dog owner, you may be in a slight panic at the prospect of your pup being contaminated with microplastics. Manly Observer reached out to local vet organisations to flag any safety concerns, with the general consensus being that there was no cause for concern.
“Microplastics are something we’re learning more about in the environment, and while pets can be exposed during normal play at the beach or park, there’s currently no clear evidence they’re causing widespread harm at typical levels. It’s still sensible to limit things like drinking from stagnant water or eating debris, just to be on the safe side,” Northside Emergency Veterinary Service told us.
Dr Timothy Hopkins from SASH Vets mirrored this statement, saying there is evidence of microplastics in companion animals, but rather it is assumed this comes from the ingestion of commercial feed and chew toys, rather than just direct contact.
“It’s certainly a marker of how messed up that environment is, but it’s much more likely to affect, you know, invertebrates, fish, turtles, the kind of animals that live in that environment full time,” Dr Hopkins said.
Is Anything Being Done?
As for the estuarine species living in these contaminated waterways, there is currently inconclusive information to determine the impact microplastics will have on them or their systems.
The report recommended conducting ecosystem impact studies to assess bioavailability, bioaccumulation, and toxicological effects on these species.
As for clean-up efforts, the State Government says it is trying to reduce plastic pollution. In line with efforts to track and tackle plastic pollution at the source, the EPA is increasing compliance with plastic bans, launching community awareness campaigns, and awarding litter prevention grants.
Under its Plastics Plan 2.0, the agency is working to phase out highly littered and avoidable plastic items – including bags with handles, bag-sealing tags, fruit and vegetable stickers – while also targeting products that break down into microplastics.
It is also running Operation Clean Sweep NSW and Operation Pellet Patrol, working directly with industry to prevent spills of plastic feedstock, such as nurdles, during transport, handling, and manufacturing.
On the waterways front, the EPA’s Streets to Sea program aims to reduce the amount of litter flowing from land into waterways, launching a new pilot specifically to map and assess litter flow in the Cooks River and Manly Lagoon. As for support on local fronts, the EPA’s Litter Prevention Program provides grants to councils to intercept litter before it reaches stormwater systems and waterways.
Northern Beaches Council currently receives $404,000 from the EPA for this purpose, with key initiatives including the Single Use Plastics Policy, community beach clean-ups, fishing tangle bins, and targeted education on illegal dumping.
