Frequently asked questions
Why not build another dam for Sydney?
Sydney is well served by its network of 11 major dams and storages. An additional dam would be very financially and environmentally costly.
A previous proposal to construct a dam at Welcome Reef on the Shoalhaven River was considered to be the best option if another dam for Sydney was needed. However this proposal would have resulted in a very shallow dam with a large surface area, meaning that evaporation rates would be extremely high, and there would be a higher risk of blue-green algae outbreaks.
The NSW Government reconfirmed in the Metropolitan Water Plan that the Welcome Reef Dam was not being considered further. The plan focuses on other, more effective opportunities to increase supply and diversify Sydney’s water sources.
Why not impose tougher restrictions?
Drought restrictions continue to play an essential role in responding to the current drought and remain an important tool for responding to future droughts. However, the NSW Government’s investments in groundwater, desalination and other measures mean that there is now no need for tougher Level 4 and Level 5 restrictions.
The next update of the Metropolitan Water Plan, will include an improved drought restrictions regime for the next drought to take account of the experiences and community responses from this drought, and new developments such as the desalination plant.
Community surveys conducted during development of the plan reported strong support for drought restrictions. Research and consultation as part of the Water For Life education program has confirmed that this support continues. The NSW Government is committed to building on this community support and has announced long term water saving rules to commence when drought restrictions are lifted.
Why don’t we just transfer more water from the Shoalhaven system?
Tallowa Dam on the Shoalhaven River was built in the 1970s and forms part of the Sydney supply system. Water is transferred from Tallowa Dam to Sydney’s other dams when supplies are low. The Shoalhaven River transfer scheme has provided about a quarter of Sydney’s water during the current drought.
Following extensive research and consultation with Shoalhaven and Southern Highlands communities, new rules have been agreed about volumes of water to be released from Tallowa Dam to benefit the environmental health of the lower Shoalhaven River, while still providing water for transfer to Sydney’s water supply when needed.
In addition, the NSW Government is investigating pipeline and tunnel options, should it decide to proceed with transfers of more water from Tallowa Dam to Sydney and the Illawarra. This would avoid the damage caused by using rivers as channels to transfer larger volumes of water when natural flows in those rivers would otherwise be low.
How much water has the deep water project given us?
Accessing previously inaccessible water from deep in the dams means that the average amount of water available in the long term has increased by 40 billion litres a year.
Sydney’s water supply system has a network of 11 major interconnected dams. To further increase available water supplies and the flexibility of this system, the Sydney Catchment Authority has completed $119 million of new works at Warragamba, Nepean and Avon Dams. This work allows previously inaccessible water at the bottom of the dams to be used if required.
In a severe drought, another 200 billion litres of water will be able to be pumped, which amounts to an additional six months of water supply. Having access to this extra water during drought times means that we can “run the dams harder”.
The new pumps at Warragamba Dam are ready to operate if the dam level falls to below 20 per cent. At Nepean Dam, the new deep water transfer pumps and pipes have already been used to pump water to the Avon Dam, to increase security of water supplies for the residents and businesses of the Illawarra region.
What’s happening with accessing groundwater?
The Metropolitan Water Plan announced that, if Sydney entered into severe drought, several borefields would be built to tap into underground water sources (groundwater). In November 2006, as drought conditions worsened, the decision was made to construct borefields in three areas pending further testing, engineering design and planning approval.
Since then, the Sydney Catchment Authority has made significant progress in investigating the potential for using groundwater from Kangaloon (in the Southern Highlands), Leonay (near Emu Plains) and Wallacia (near Warragamba).
At Kangaloon, extensive investigations, trials and research, which have been independently audited by groundwater experts, indicate that substantial groundwater volumes can be delivered. Trial bores have now produced nearly 0.5 billion litres of water, which was fed into streams above Nepean Dam. Recent monitoring has confirmed that, after pumping takes place, heavy rainfall events can recharge this groundwater source relatively quickly. During the pumping trial, the extent of water level decline was less than expected and there were no identified impacts to the environment or local groundwater users. Further investigations and community consultation will continue as part of the final borefield design and planning approval process.
The Leonay and Wallacia sites are at earlier stages of investigation, but all indications are that significant volumes of groundwater are available in the deep sandstone rocks. A staged process of initial drilling, follow-up targeted drilling, pilot studies, community consultation and extended pumping trials were undertaken throughout 2007.
Under the plan, these borefields would operate during severe drought for two to three years and would then be turned off to recharge. Current estimates suggest that up to 45 billion litres of groundwater would be available each year from the three borefield areas for two to three years.
How much water would the three groundwater bore fields provide?
At Kangaloon, extensive investigations, trials and research, which have been independently audited by groundwater experts, indicate that substantial groundwater volumes can be delivered.
Under the plan, the borefields would operate during severe drought for two to three years and would then be turned off to recharge. Current estimates suggest that up to 45 billion litres of groundwater would be available each year from the three borefield areas for two to three years.
Would the groundwater project damage the environment?
At Kangaloon, extensive investigations, trials and research, which have been independently audited by groundwater experts, indicate that substantial groundwater volumes can be delivered. Trial bores have now produced nearly 0.5 billion litres of water, which was fed into streams above Nepean Dam.
Recent monitoring has confirmed that, after pumping takes place, heavy rainfall events can recharge this groundwater source relatively quickly. During the pumping trial, the extent of water level decline was less than expected and there were no identified impacts to the environment or local groundwater users. Further investigations and community consultation will continue as part of the final Kangaloon borefield design and planning approval process.
The Leonay and Wallacia sites are at earlier stages of investigation, but all indications are that significant volumes of groundwater are available in the deep sandstone rocks. A staged process of initial drilling, follow-up targeted drilling, pilot studies, community consultation and extended pumping trials were undertaken throughout 2007.
What’s happening with desalination?
The Metropolitan Water Plan included a provision for awarding construction contracts for a desalination plant in the event that extreme drought conditions saw storage levels fall to record lows.
In accordance with the Plan, the Government decided on 6 February 2007 to issue a request for tenders to build the desalination plant. At the time, storages were at 34 per cent and shortly afterwards fell to 33.8 per cent - their lowest ever since the construction of Warragamba Dam.
Sydney Water has signed contracts with the Blue Water Joint Venture (Veolia Water and John Holland) and the Water Delivery Alliance (Bovis Lend Lease, McConnell Dowell, Kellogg Brown & Root, Patterson Britton & Partners and Environmental Resources Management) to build a 250 million litres a day desalination plant and associated pipeworks at an estimated cost of $1.833 billion. The plant will be powered by 100 per cent accredited renewable energy - making the desalination plant carbon neutral. The plant’s capacity can also be quickly doubled again if needed, without further pipeline construction.
A site at Kurnell has been cleared and initial construction work has commenced. The route of the pipe, which will take the drinking water into the water supply network, is being finalised, with community consultation. A comprehensive Environmental Assessment (EA) has been completed and has been available on both the Department of Planning website and the Sydney Water website since November 2005. An EA on the pipeline is also available. Both can be found at http://www.sydneywater.com.au
Why are we building a desalination plant when it has rained?
While Sydney was fortunate to receive rain following the decision to build the desalination plant, the plant will still go ahead to ensure Sydney’s water supply for the future.
The 2006 Metropolitan Water Plan states that construction contracts for a desalination plant would be awarded in the event that extreme drought conditions saw storages fall to record lows (about 30 per cent). In accordance with the plan, the NSW Government decided on 6 February 2007 to issue a request for tenders to build the desalination plant (a necessary precursor to entering into a construction contract). At that time, storages were at 34 per cent and shortly after that fell to their lowest level since the construction of Warragamba Dam.
Had dam levels continued to decline at the rates observed in preceding months, storages would have been approaching 30 per cent in April and critical levels by mid 2009. Without action, Sydney’s drinking water would have been under serious threat, because a 26 month construction timetable meant that storages could have reached the critical level before desalinated water would have been available. Many cities around the Australia and the world are in the queue for the limited expertise and resources needed for the construction of desalination plants. This posed a risk that crucial desalination expertise and materials would not have been available to Sydney in time if the decision to construct had been delayed.
The NSW Government determined that the request for tenders would be accompanied by a firm commitment to construct the plant in order to provide certainty to industry and facilitate an efficient procurement process.
That firm tender process has delivered a competitive proposal which will deliver a plant with twice the capacity for about the same projected cost of the original sized plant. Importantly, the plant’s capacity can be quickly doubled again if needed, without further pipeline construction.
Does the desalination plant mean we can lift water restrictions now?
The Government has indicated that it will not move prematurely to lift restrictions, noting that storage levels may again decline. The Government will seek expert advice on rainfall projections prior to making a decision on easing water restrictions.
The prime advantage of desalination over most other water supply sources is that it is not dependent on rainfall and, hence, insures against both short-term drought and the potential long-term impacts of a changing climate. While there is no single solution to all of Sydney’s water needs, having desalination as one of the initiatives in a portfolio of water supply and conservation measures – alongside recycling, water savings programs and restrictions - means that Sydney’s water supply system is more reliable, diverse, flexible and integrated than ever before.
While recent rain has boosted levels in the Sydney storage system, we cannot be complacent. We have previously seen storage levels rise – as occurred in early 2006 – only to fall again and reach record lows earlier in 2007.
Will the desalination plant have impacts on the environment and the community?
The Government is committed to minimising environmental impacts associated with the plant – both during construction and operation of the plant.
A comprehensive Environmental Assessment (EA) has been completed and has been available on both the Department of Planning website and the Sydney Water website since November 2005. An EA on the pipeline is also available. Both can be found at http://www.sydneywater.com.au.
Like all major projects, construction will involve some temporary impacts on the environment and the community, but every effort will be made to minimise such impacts.
The desalination project will be subject to strict environmental management conditions imposed by the Minister for Planning.
Sydney Water is required to put in place a range of on-going environmental management plans to protect the land and marine environment during and after the construction.
What’s next?
To ensure that Sydney’s water supply system becomes more reliable, diverse and flexible the next steps are to:
- Develop an optimised restrictions regime for the next drought based on lessons learnt from this one
- Begin construction of the desalination plant. The plant will be ready to deliver 125 million litres a day by October 2009 and 250 million litres a day by early 2010
- Finalise investigations of the three groundwater sources as a drought supply
- Continue evaluating new pipe and tunnel delivery options should the Government decide on any further Shoalhaven River transfers
- Assess other possible water supplies when updating the plan.