Warragamba Dam is located adjacent to Sydney’s untouched Greater Blue Mountains World Heritage Area. In 2016, the NSW Government allocated $30 million to begin plans to raise Warragamba Dam for downstream flood mitigation. Raising the dam would destroy large areas of Sydney’s pristine water catchment at a cost of over $700 million ($400 per Sydney household). The dam raising is being pushed by developers wanting to spread urban sprawl across western Sydney floodplains.
The push of urban sprawl
The NSW Government has said the raising of Warragamba Dam will allow them to open 2,355 hectares of western Sydney floodplains to urban sprawl by creating flood mitigation capacity in the existing dam. This equates to an addition 94,000 houses squashed into western Sydney. This is a seriously dangerous idea.
The move area on the above map shows land earmarked for urban sprawl, and the blue area Hawkesbury-Nepean floodplains. Property developers think that raising Warragamba Dam will allow them to claim thousands of new houses they build on floodplains (overlap of pink and blue) will be safe from flooding. This will put thousands of human lives at risk, with a raised dam only having marginal impacts on reducing downstream floods.
An improper solution
Warragamba dam has supplied clean drinking water to Sydney for the last 60 years. It was not designed as a flood mitigation dam. Raising the dam will put at risk Sydney’s pristine water catchment and cause enormous environmental damage to the wild rivers and wilderness upstream of the dam.
- The Warragamba River makes up only one half of the catchment area of the Hawkesbury-Nepean Valley. Flood waters originating from the south-eastern and northern half of the catchment would not be mitigated against and would still cause considerable flooding
- Raising the dam would not have a significant impact on reducing downstream flood peaks
- Raising the dam will encourage high density urban sprawl across western Sydney low-lying floodplains that would be at risk from flooding
- Raising the dam would have significant effects on Sydney’s water quality. Erosion of sediment, dying organic matter and river bank slumping will input millions of tonnes of sediment into the Warragamba Dam
- Raising the dam will flood 65 kilometres of wild rivers and 4,700 hectares of national parks. To find out more about environmental impacts, head to Wilderness Impacts
Governments should not allow the building houses on floodplains. It is a dangerous pursuit that will end in tragedy. For existing communities, there needs to be a multifaceted approach to flood management that protects human lives while ensuring that we don’t ruin one of the most extensive World Heritage Areas in Australia. We must accept the reality that floods occur and make sure we manage them properly. These include:
- Not dramatically increasing the risk to life by housing an additional 130,000 people on the floodplain. The consequences of this were seen during the 2011 Brisbane floods
- Ensuring people can get out in time by high-level flood evacuation routes
- Allowing the floods room to move on the floodplain using levies and diversion banks
- Development controls that reflect the seriousness of flood risk
- Managing the capacity of the existing dam