Draft Mosman Flood Study Exhibition Period CLOSED

The Mosman Local Government Area (LGA) Draft Mosman Flood Study (the study) provides flood information for the Mosman area based on analysis of various rain events and how they may flood parts of Mosman. Community members provided historical flood information in response to a survey distributed in late 2023. This information has been used by Manly Hydraulics Laboratory (MHL) alongside modelling based on data collected and best industry practice to finalise the Draft Mosman Flood Study.

The study was on exhibition until 11:55pm 30 September 2025 AEST and can still be accessed here.

Link to an interactive map (deactivated), this will allow you to see those properties that have been identified as being in the preliminary Flood Planning Area.

Why is Council doing a flood study?

All councils are required to assess and plan for the risk of flooding. The NSW government outlines the risk management process in the Flood Risk Management Manual, June 2023. The Mosman Flood Study will:

• provide information to support new developments, property improvements and flood risk management in the interest of protecting all property owners.
• inform State Emergency Service (SES) and Council to plan and manage emergencies, enhance community preparedness and minimise impact on vulnerable communities and key infrastructure.
• ensure new developments do not make flooding worse.
• create a foundation for further design, assessment and planning for Council's infrastructure upgrade.
• enable Council to proceed with the flood risk management process and seek grants for work including to improve Council's stormwater infrastructure and reduce the risk of flooding.

Summary of information available

Council encourages the community to view the study to see what it indicates in relation to impact, if any, on private property or other land. You can also:

• View an interactive map  (deactivated) that identifies locations within the Mosman LGA with the potential to be affected as they are identified in the draft study a being in the preliminary ‘Flood Planning Area’ (FPA).
• View video presentations on this page by NSW Department of Climate Change, Energy, Environment and Water (DCCEEW) and Manly Hydraulics Laboratory.
• See Frequently Asked Questions (FAQs) and answers on this page.
• Email floodstudy@mosman.nsw.gov.au or phone 1800 228 554

Next Steps

• The Final Flood Study will be completed based on community feedback and then endorsed by Council
• A Flood Risk Management Study and Plan, with a suite of flood management measures will be developed.
• Flood management measures will be implemented