Raising Cooma Levee - Concept Design and Feasibility Study

Project Type: Concept design and feasibility study

Project Location: Cooma

Funding: NSW Government Grant

Timeline updated to reflect additional flood modelling and design work required under updated climate change guidelines.

What are we doing?

To reduce the impacts of flooding in Cooma, Council is undertaking a project to develop a concept design and feasibility assessment for flood levee options along Cooma Creek.

The project will identify a preferred levee option that could be progressed to detailed design and potential construction in the future. This work includes technical investigations, cost assessments, and consultation with the community, agencies, and stakeholders.

Stage 1 – Selection of preferred levee option - Completed

Stage 1 focused on developing and assessing possible levee options. This included:

• Collection and review of existing data, previous studies and investigations
• Utilities and physical constraints assessment
• Development of multiple levee design options
• Hydraulic and economic analysis of options, including:
  • Flood levels and freeboard
  • Potential impacts on surrounding properties
  • Internal drainage considerations
  • Land impacts and constraints
• Community, agency and Council consultation
• Assessment and selection of a preferred levee option

Stage 2 - Detailed assessment of the preferred levee option

 Stage 2 is examining the preferred levee option in more detail and has been expanded to include additional work following updated climate change guidance. This stage includes:

• Survey and geotechnical investigations
• Development of refined concept designs
• Detailed hydraulic and economic assessments
• Consideration of internal drainage and land access requirements
• Preliminary environmental assessment
• Community and agency consultation
• Finalisation of concept designs and feasibility assessment

Latest Update - March 2026

Council has extended the project timeframe to ensure the levee designs meet new national climate change requirements and provide the best possible long‑term flood protection for the community.

Since the project started, updated guidance under Australian Rainfall and Runoff 2019 (ARR v4.2) has been released. This guidance significantly increases the climate change allowances that must be applied to future flood modelling for Cooma.

As a result, additional technical work is required to:

• Update the Cooma hydrologic and hydraulic flood models using the latest climate change scenarios
• Reassess freeboard requirements for both the 5% and 2% Annual Exceedance Probability (AEP) flood events under climate change conditions
• Update the current levee design to provide 5% AEP climate change protection plus freeboard
• Develop an additional levee option that would provide 2% AEP climate change protection plus freeboard
• Prepare an updated cost–benefit analysis comparing both levee options

This extra work ensures the project is based on the most up‑to‑date science, meets State agency requirements, and allows Council and the community to clearly understand the benefits, costs and implications of different protection levels before any future decisions are made.