Floods

How we manage our dams during a flood event is determined primarily by the following:

• WaterNSW Act 2014
• Operating Licence - WaterNSW may undertake flood mitigation only if authorised to do so
• Water Sharing Plan (WSP) / works approval - specifies dam operations during floods along with airspace operation rules

Along with the rules outlined above, WaterNSW has various responsibilities including adhering to best practice flood operations and the NSW State Flood Plan. The latter includes:

• Information sharing with The Bureau and NSW SES
• Where applicable, work with The Bureau and NSW SES to manage releases to reduce impacts
• Hydrometrics
• WaterNSW Flood Incident Management Protocol

Flood Operations in Regional NSW

In regional NSW, WaterNSW is able to act in a flood mitigation capacity. This means that we are able to release water before an event in order to create airspace for the forecast rain. Airspace targets are determined in consultation with Airspace Reference Panels, made up of local community members. Minutes from Airspace Reference Panel meetings can be found on WaterInsights.

During a flood event we then hold releases, if possible, until flood waters have receded.

Flood operations objectives:

• Ensure the safety of the structure
• End the flood with the storage at target level (Full Supply Level or a pre-release target)
• Mitigate the effect of flood as far as possible.

Flood Operations in Greater Sydney

WaterNSW is not permitted under the regulatory framework governing Greater Sydney dams to operate any Greater Sydney storage for flood mitigation purposes.

This is because Greater Sydney dams are classified as water supply dams, responsible for the water security of the five million people who reside in Greater Sydney.

Flood operations objectives:

• Ensure the safety of the structure
• End of the flood with the storage at target level (Full Supply Level).

Outside of flood operations, the storage level at Warragamba Dam may be temporarily drawn down by up to 1m below Full Supply Level to safely facilitate necessary maintenance activities.