WaterNSW Response to Greater Sydney Catchment audit

WaterNSW Response to Greater Sydney Catchment audit

19 August 2020

Has there been a substantial increase in blue green algae alerts for Greater Sydney catchments since the previous audit?

There was a 56% increase in blue green algae alerts in the 2016-2019 audit period when compared to the 2013-2016 audit period. The auditor stated that this increase is due to ongoing drought conditions experienced within the region in 2017-2019, which generally promotes favourable conditions for algal bloom growth including reduction in flow and high-water temperatures.

It’s important to note that only two sites reported red alerts during 2016-2019 – Lake Wallace and Lake Lyell. These are owned and managed by Energy Australia associated with Mt Piper power station and are lakes where raw water for drinking water and subsequent treatment is not directly sourced.

Due to drought conditions during the period of the audit it is important to note that apart from small required environmental releases, minimal flows from these lakes would have been released into Coxs River.

WaterNSW constantly monitors water quality in Warragamba dam. Our extensive monitoring program is designed to provide early warning of potential increases in algal activity, allowing us to proactively manage changes in raw water quality. For example, if required we can move to take water from different levels in the storage to avoid blue green algae which generally sits on the surface.

WaterNSW has also instigated a range of monitoring and science projects to gather data about any compounds which have washed off the areas of the catchment burnt by the recent fires to ensure we build an understanding of any other changes in the characteristics of the water in the dam over the longer term and can develop adequate mitigation strategies if required.

How is WaterNSW combating issues related to climate change?

The independent auditor identified a number of emerging risks to the Greater Sydney catchments, which is important to help the relevant authorities head-off potential risks and clearly identify opportunities for ongoing improvement.

Key issues identified in the audit report such as meeting the challenge of climate change, and its link to managing Sydney’s water source sustainably, are key features of the State Government’s Greater Sydney Water Strategy, currently in its final stages of development. WaterNSW will continue working to understand how to combat the changing nature of catchments.

The audit states that priority areas for improvement are the Upper Coxs River (Lithgow) and Wingecarribee River (Bowral) sub-catchments. How is WaterNSW working to reduce pollution in these areas?

WaterNSW is committed to ensuring the quality of water in Sydney dams is protected. This requires a range of actions to ensure that water in the catchment and rivers that flow into the dams is not polluted. The NSW EPA undertakes a range of water pollution control activities across the catchment and WaterNSW and Councils work in conjunction with the EPA to prevent and minimize water pollution.

Key actions going forward to reduce pollution in the Lithgow and Bowral areas include:

  • Upgrades to sewerage infrastructure in the Wingecarribee Council area including at the Bowral, Moss Vale and Mittagong sewerage treatment plants.
  • Strategic investigations into water pollution in the Lithgow and Bowral areas and the implementation of programs to address the outcomes of these investigations. Focus will be on EPA licenced activities and reducing algae in Lake Lyell, Lake Wallace and Lake Wingecarribee.

The audit acknowledges that Sydney’s is a living catchment, in that a large population lives within its boundaries and a wide range of industrial and commercial activity takes place, and in some cases has done so for more than a century, including mining and agriculture.

It is well-recognised that this activity produces – or has produced historically – potential contaminants and pollutants, the risk of which must be mitigated in the catchment as the first and principal line of defence in protecting the source of Sydney’s drinking water.

The audit raises some concerns about mining in the catchment, how does WaterNSW respond to these concerns?

WaterNSW long-held and public position is that longwall mining in particular, especially in key areas of the catchment (Special Areas), poses an unacceptable risk to catchment water resources.

Earlier this year WaterNSW welcomed confirmation of further protections for Sydney’s drinking water catchment consistent with critical reforms advocated by WaterNSW in its role as catchment protector.

WaterNSW has been working co-operatively with the NSW Government and the mining industry to introduce measures to further reduce the risk posed by mining to the quality and quantity of water in the Greater Sydney catchment.

WaterNSW strongly supports the government’s stated objective of avoiding future water losses due to mining activity, and if losses occur, that mining companies must offset or compensate, resulting in a net gain for the metropolitan supply.

How does WaterNSW intend to respond to areas of needed improvement highlighted by the audit?

The independent Sydney drinking water catchment audit evaluated the condition of the catchment, and the actions of several local and state government authorities, including WaterNSW, against several key indicators.

WaterNSW will review the audit report’s findings and recommendations relevant to its operations and report back to government.

Importantly, the report notes that the management of the catchment has experienced continued “substantial improvement” in recent decades, including:

  • The implementation of new systems, risk assessments, plans to protect water quality and catchment health, and more comprehensive monitoring activities;
  • Local and state planning control reforms to protect water quality;
  • Increased restrictions on mining and;
  • The implementation of a range of measures which either removed or reduced pollutant sources.


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