CSIRO Report Highlights Potential of Dams in Mitigating Lismore Floods

The Commonwealth Scientific and Industrial Research Organisation has released findings showing that strategic water detention infrastructure could have substantially lessened the impact of the devastating 2022 floods in Lismore and surrounding Northern Rivers communities. The report, part of the Northern Rivers Resilience Initiative, models how up to ten new detention basins might have lowered peak water levels by as much as two metres during the record-breaking event.

Released on 30 June 2026, the study draws on advanced hydrological modelling of the Richmond River catchment. It provides a detailed blueprint for future flood resilience measures in one of Australia's most flood-prone regions. While the measures would not have eliminated flooding entirely, they represent a significant step toward reducing damage to homes, businesses, and critical infrastructure.

Recalling the Scale of the 2022 Northern Rivers Floods

In late February 2022, the Northern Rivers region of New South Wales experienced one of the most extreme flood events in living memory. Lismore recorded a peak of 14.37 metres at the local gauge, more than two metres above previous major flood levels from 1954 and 1974. The waters overwhelmed the town's levee system, leading to widespread inundation of the central business district and residential areas.

Thousands of residents were displaced, with emergency services stretched to capacity. The event caused billions of dollars in damages across multiple local government areas including Lismore, Ballina, Byron, and Tweed. Recovery efforts continue years later, underscoring the long-term social and economic toll of such disasters.

Understanding the CSIRO Modelling Approach

Scientists at CSIRO developed a high-resolution virtual model of the Richmond River catchment to simulate flood behaviour under various scenarios. The model incorporates detailed data on rainfall patterns, river flows, topography, and existing infrastructure such as levees and pumps.

Researchers tested multiple combinations of mitigation options, referred to as bundles. These included new detention basins designed to temporarily store floodwaters and release them gradually. The analysis compared outcomes against historical events and projected future conditions influenced by climate variability.

Key Findings on Flood Level Reductions

The most effective configuration, known as Bundle 2, demonstrated the potential to reduce peak flood heights at Lismore by up to 2.07 metres during the February 2022 event. Similar reductions were modelled for other historical floods, including 2.37 metres in 2008 and 1.40 metres in 2017.

Across the broader Northern Rivers, water levels at key gauges in Casino, Coraki, and Ballina also showed meaningful decreases. The detention basins would capture and hold excess water during intense rainfall periods before controlled release downstream.

Limitations and Realistic Expectations

Despite the promising reductions, the report emphasises that even the optimal bundle would not have prevented the Lismore CBD levee from overtopping. The structure experienced a 3.8 metre over-topping in 2022, and the modelled mitigation fell short of fully containing such an extreme event.

Experts note that detention basins provide temporary storage rather than permanent holding capacity like traditional dams. This distinction is critical for community understanding and expectations around flood protection.

Photo by Brett Jordan on Unsplash

Broader Implications for Australian Flood Management

The findings contribute to ongoing national discussions about infrastructure investment in flood-prone areas. New South Wales authorities and federal agencies are reviewing the report as part of wider resilience planning.

Similar modelling approaches could inform strategies in other vulnerable catchments across Queensland, Victoria, and beyond. Integrated solutions combining detention basins with upgraded levees, improved drainage, and early warning systems are likely to form the core of future recommendations.

Access the official CSIRO Northern Rivers Resilience Initiative overview for additional technical details.

Community and Stakeholder Perspectives

Local residents and business owners in Lismore have expressed cautious optimism about the report. Many welcome evidence-based options after years of uncertainty following the 2022 disaster.

Some community groups highlight the need for complementary measures such as property buybacks in high-risk zones and enhanced emergency response protocols. Government representatives have indicated the findings will guide prioritisation of projects under existing funding programs.

Economic and Social Impacts of Improved Mitigation

Reduced flood heights would translate into fewer evacuations, lower property damage, and faster recovery times. The 2022 event resulted in thousands of displaced people and significant disruption to local economies reliant on agriculture, tourism, and small business.

Modelling suggests that even partial reductions in water levels could save millions in direct damages and indirect costs such as lost productivity. Long-term benefits include greater confidence for investment and improved mental health outcomes for communities repeatedly affected by flooding.

Climate Context and Future Risks

The report situates the 2022 floods within a changing climate where extreme rainfall events may become more frequent or intense. Catchment-specific modelling helps planners account for these variables when designing infrastructure.

CSIRO scientists stress that no single solution offers complete protection. A layered approach combining structural measures with non-structural strategies such as land-use planning and community education remains essential.

Next Steps and Policy Recommendations

Following the release, consultations with local councils, Traditional Owners, and residents are expected to refine preferred mitigation bundles. Funding pathways through state and federal programs will determine implementation timelines.

Further detailed engineering studies and environmental assessments will be required before any construction proceeds. The CSIRO model itself will serve as an ongoing tool for testing additional scenarios.

Photo by Bernd 📷 Dittrich on Unsplash

Looking Ahead: Building Resilient Communities

The CSIRO report provides a valuable evidence base for decision-makers grappling with complex flood challenges. While dams and detention basins offer meaningful reductions, they form part of a broader toolkit needed to safeguard the Northern Rivers and similar regions.

Continued investment in science, infrastructure, and community preparedness will be key to minimising future losses. The lessons from Lismore underscore the importance of proactive, data-driven approaches to natural hazard management across Australia.