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Living in a beautiful coastal area traversed by creeks and dotted with coastal lagoons comes with the risk of flooding. Northern Beaches Council continues to undertake a program of studies and investigations to identify the areas at risk of flooding and how this can be managed.   

Types of Flooding

Floods can be dangerous. You should never enter flood waters. There are two kinds of floods that occur naturally on the Northern Beaches: flash floods and lagoon flooding. 

Flash Floods

Flash floods occur when heavy rainfall causes creeks to break their banks or the stormwater network to exceed its capacity and overflow. Flash floods happen suddenly with little or no warning and recede relatively quickly.

Lagoon Flooding

Lagoon flooding occurs when creeks and stormwater networks drain into lagoons during major storms. The lagoons rise from rainfall runoff and ocean swells resulting in flooding of the area around them. Water levels drop when flood waters can escape through the lagoon entrance. Tides and wave movement play a significant part, and this may take a long time.

Further information on the opening and closure of coastal lakes and lagoons can be found at Department of Primary Industries 

What we do to Reduce Flood Risk

Council follows the NSW Government’s floodplain risk management process to identify and manage flood risk.  This is a four stage process resulting in an adopted plan for managing flood prone land:

1. Flood Study – identification of flood risk

2. Floodplain Risk Management Study – identification and assessment of a range of floodplain management options to reduce flood risk

3. Floodplain Risk Management Plan – a comprehensive plan setting the strategic direction for the management of flood prone land through the implementation of a range of options

4. Implementation of Floodplain Risk Management Plan – implementation of floodplain management options in accordance with priority and financial constraints.

Planning Controls for Flood Prone Areas

One of the principal recommendations for managing flood risk is the adoption of planning controls for flood prone areas. Planning controls, sometimes known as flood related development controls, include the setting of floor levels above known flood levels. These ensure the end use of a development is compatible with the known flood hazard.

You can search for your properties flood related development controls and flood hazard map on the Planning Rules page

Northern Beaches Flood Information Network

Northern Beaches Council in conjunction with the State Emergency Service and Manly Hydraulics Laboratory have established an innovative online flood warning system for the region. The system involves the installation of a number of rainfall and water level gauges that provide live data on where and when flooding may occur, lagoon levels, weather warnings and any recent or forecast rainfalls. 

What you can do to Protect your Home and Family

If your property’s on flood prone land be prepared and vigilant. Use the online flood warning system for up-to-the-minute news on current rainfall, flood warnings and safety advice. Also, the SES FloodSafe website can alert you on flooding in your area.  Call for emergency help in flood, storm and tsunami on 132 500.

Flood Studies

Flood studies improve our understanding of flood behaviour, in particular the speed and depth of flood water, and to identify problem areas. 

Flood Study Documents

View the list of all council flood study documents.