Questions and Answers

Questions and Answers

Find key facts and commonly asked questions about the Proposal below.

Technical studies and survey data findings informed the Environmental Impact Statement, which was publicly displayed in 2021. You may still view the EIS document on the Department of Planning and Environment portal.

There is a very real and substantial existing risk to life, property and community from rapid and deep flooding in the Hawkesbury-Nepean Valley after significant rainfall events.

The proposal to raise Warragamba Dam for flood mitigation, would significantly reduce risk to people’s lives and livelihoods downstream, provide more time for evacuation and reduce flood damages by 75% on average.

For more information please see the ‘Land Use in the floodplain’ fact sheet on the Infrastructure NSW website at Hawkesbury-Nepean Valley Flood Risk Management Strategy.

Australia’s obligations under the World Heritage Convention; the Australian World Heritage management principle; and the Greater Blue Mountains World Heritage Area (GBMWHA) Strategic Plan were included in the consistency report which formed part of the Environmental Impact Statement (EIS). There would be offsets proportionate to the impacts so that on balance there is no net loss to the values and improved integrity

The EIS was publicly displayed in 2021. You may still view the EIS document on the Department of Planning and Environment portal.

The extent and duration of temporary inundation depends upon the size of the inflows event and the starting level of the storage at time of the event. Every flood is different, so extensive modelling of the full range of variables was undertaken. This gave a realistic representation of thousands of hypothetical flood events that were used to determine that the likely inundation

There is only one declared wild river located in the Warragamba Dam Catchment – the Kowmung River. Based on modelling, there would be no change to the level or extent of inundation for the declared section of the Kowmung River, its streams or tributaries, with the proposed wall raising. As part of the environmental assessment, the impact of temporary inundation on other rivers and streams has been analysed.

Flooding of areas upstream of Warragamba Dam happens now during significant rainfall events.

Comprehensive ecological studies have been undertaken to assess the impacts of a temporary increase in upstream inundation as a result of the proposal to raise Warragamba Dam for flood mitigation. This assessed impacts on threatened plant, animals and ecosystems and identifying measures to mitigate impacts where possible. The findings informed the Environmental Impact Statement (EIS), displayed in 2021. You may still view the EIS document on the Department of Planning and Environment portal.

A detailed Aboriginal Cultural Heritage Assessment has been undertaken as part of the environmental assessment process. This process has been developed in collaboration with Registered Aboriginal Parties.

The impacts on Aboriginal cultural heritage values from infrequent and temporary upstream inundation and options for minimising the impacts, have been included in the Environmental Impact Statement.

Registered Aboriginal Parties have participated in the field surveys, will review the Aboriginal Cultural Heritage Assessment Report, and are being consulted on the proposed options for mitigating and minimising impacts.

There are a number of ways the community has had the opportunity to provide input to the Environmental Impact Statement which included:

  • directly contacting the project team by email, phone or letter to provide feedback
  • participating in the surveys for the socio-economic impact assessments
  • talking to the project team at information sessions, community workshops, briefings or community forums
  • making a formal submission to Department of Planning and Environment when the Environmental Impact Statement was on public exhibition.

Our community webpage provides a detailed breakdown of the engagement activities undertaken to date.

To raise awareness in the community regarding the role of the environmental assessment and to engage with the community and other stakeholders at a stage when the scope of the project and environmental assessment can be influenced.

Community engagement ensures information about the proposal, and the environmental assessment process, are known so community members can have their say. The Environmental Impact Statement was publicly displayed in 2021.

The proposal to raise Warragamba Dam for flood mitigation will be considered under both NSW and Australian Government legislation. Construction can only begin if the environmental and planning approvals are granted and once the NSW Government has made a decision on a final business case.

WaterNSW made the Environmental Impact Statement (EIS) publicly available in 2021. The EIS was publicly exhibited from the 29th of September to the 19th of December 2021. You can view the EIS document on the Department of Planning and Environment portal.

Importantly, the final decision on the dam raising proposal will only be made after all environmental, cultural, financial and planning assessments are complete.

Contact the Warragamba Dam Raising team:

Call: 1800 932 066


The Flood Strategy

Contact the Hawkesbury-Nepean Valley Flood Risk Management Directorate, Infrastructure NSW on:


The Flood Strategy is available online at:


Sunday 03 July
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Sunday 03 July