The lasting damage from the 2022 floods on the Richmond River has been the focus of a new study, with researchers claiming that it is ‘the clearest evidence yet that the vast majority of sediment pollution starts far upstream’.
In a media release, independent community organisation Richmond Riverkeeper say the study, Sediment Pollution Sources to the Richmond River, was conducted by Rous County Council in partnership with Griffith University and released this week.
‘It will serve as a key blueprint for restoration under the Richmond River Coastal Management Program (CMP)’.
‘The research found that 84% of sediment deposited in the river’s coastal zone originates from the middle and upper reaches of the catchment, with erosion hotspots concentrated in the Kyogle and Richmond Valley local government areas. Channel erosion was identified as the dominant cause of sediment pollution — a process that clouds waterways and degrades the aquatic ecosystems communities rely on.
‘Using post-flood LiDAR data, researchers identified approximately 1,600 landslides triggered by the 2022 floods, which contributed around one million cubic metres of eroded material to the system. Much of this is coarse sediment — sand that moves slowly through river systems — meaning the legacy of those floods will be felt across the catchment for years.
Citizen science eco-health monitoring
Richmond Riverkeeper’s Dr Adele Wessell said the findings aligned closely with the organisation’s own citizen science eco-health monitoring.
‘Our Richmond River EcoHealth Report Card consistently shows good water quality, but the waterbugs tell a different story. They are fighting over limited habitat, and we’re seeing a reduction in macroinvertebrate biodiversity as a result. Before the 2022 flood, habitat availability wasn’t a significant issue — that’s changed. The SIGNAL biplot in our Autumn 2024 Report Card makes this visible.’
‘This new research helps explain why. The landslides introduced coarse sediments like sand that take much longer to move through the system than the fine silt that causes high turbidity. The upstream impacts are ultimately what determine river and estuary health downstream.’
Richmond Riverkeeper say they welcome the study as a critical step toward evidence-based, targeted restoration — and calls for investment in remediation works in the identified hotspot areas of the upper and middle catchment to be prioritised under the CMP.
Read more about the Richmond River EcoHealth Citizen Science Project here.
About Richmond Riverkeeper
Richmond Riverkeeper is an independent community organisation working to make the rivers of the Richmond catchment swimmable, fishable and drinkable again. Through advocacy, research, citizen science and community engagement, we give voice to the river and the people who depend on it. richmondriver.org.au Join the Riverkeeper and add your voice for the river.
The lands and waterways of the Richmond Catchment are the unceded territories of the Bundjalung and Githabul Nations.
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