Thursday, October 23, 2008

Finding water for Sydney

An article in today’s Sydney Morning Herald (online) reports on a speech given by NSW Premier Nathan Rees in Sydney this afternoon. In his speech, Mr Rees justified the construction of the Sydney desalination plant on the basis that the Sydney Catchment Authority (SCA) was sourcing “roughly half” of the water it supplies from the Shoalhaven catchment:

“Later in his speech, Mr Rees told the audience that Mr Iemma had warned him not to speak about something while he was water minister.
"The former premier wouldn't let me say this, but I can say it now: we transfer roughly half of our water supply each day up from the Shoalhaven River in the south.
"In February last year, in the middle of the worst drought in 100 years, if we hadn't been transferring water from that river, and if we hadn't had water restrictions on, our water supply would have been down to 7 per cent.
"Now that's a scary figure. That essentially means people are drinking mud."
He explained that it was vital for a city as large as Sydney to have a guaranteed water supply via a desalination plant.
"If we don't establish a water supply that is independent of rain, we cannot guarantee water supply.
"If you cannot guarantee water supply, you cannot guarantee the economy and if the NSW economy ... gets the wobbles, Australia gets the wobbles.
"The desalination plant enables us to tap into the world's biggest dam - the ocean."

The transfer of water from the Shoalhaven is certainly an expensive, energy-intensive and ultimately unsustainable way to provide water for Sydney. However, the extent of the transfers appears to have been somewhat exaggerated by Mr Rees and his solution simply doesn’t stack up.

A detailed water balance for the 2006/07 financial year is publically available on the Sydney Catchment Authority website (which makes Rees’ alleged gag by Iemma seem somewhat silly).

The SCA water balance shows total transfers from the Shoalhaven to the Warragamba supply system during 2006/07 to be 98 gigalitres (98,000 megalitres). By comparison, total water supplied to customers was 507 gigalitres. An additional 94 gigalitres were lost by evaporation from storages, 56 gigalitres were released under water management licences and 572 gigalitres were spilled from reservoirs or weirs.

By any reasonable calculation, the SCA supplied at least 1,229 gigalitres (507 + 94 + 56 + 572) to either people or the environment during 2006/07. Of that, 98 gigalitres came from the Shoalhaven, which accounts for about 8 per cent. Even calculated as a proportion of the amount directly supplied to customers, this is less than 20 per cent.

Admittedly, these numbers are derived from averages over the entire year and it is quite likely that the proportion supplied from the Shoalhaven during February 2007 was significantly greater. However, that’s why we have such enormous dams as Warragamba, -to allow us to buffer our water inflows and outflows over a period of years.

With Sydney’s dams currently two thirds full, if we really are transferring half our water each day from the Shoalhaven as Mr Rees has stated, he really should demand a stop to it. We currently have plenty of water, its raining cats and dogs and the Shoalhaven should run free.

Now, considering viable solutions to curb some of this pumping back in 2006/07, the NSW State Government’s answer was to build a seawater desalination plant. That plant will supply up to 90 gigalitres of water per year (that’s less than 8% of our total water supply).

Meanwhile Sydney Water discharges around 400 gigalitres of wastewater into the Pacific Ocean every year. Even capturing and reusing half of this would provide more than twice as much as is currently supplied from the Shoalhaven or is intended to be supplied by seawater desalination in the future.

So an expensive, energy-intensive seawater desalination plant may well replace an expensive, energy-intensive inter-basin water transfer to supply Sydney with about 8 per cent of our water. However, a water recycling scheme, treating water from our coastal sewage treatment plants, could actually increase the available water for Sydney, reduce ocean pollution and relieve some pressure from our already stressed natural water supplies. Just a thought...


Anonymous said...

I couldn't agree with you more. It's a shame that NSW couldn't take a leadership role on recycled water and instead declared that the public wouldn't accept it.

Stuart Khan said...

A quick update today, with an agreeable comment from the Total Environment Centre at the end...

Here's mud in your eye: water plant saves Shoalhaven
The Sydney Morning Herald, November 7, 2008
By James Woodford

THE pumping of water from the Shoalhaven River to top up dam supplies for the Sydney metropolitan area will be arrested for at least three years, and suggests that the city's water crisis has eased further.

Today the NSW Minister for Water, Phillip Costa, will announce a suspension of water transfers from the Shoalhaven to metropolitan dams.

Since 2003 more than 810 billion litres of water has been transferred from the river to drought-proof the city.

Without the transfers Sydney would have run out of water, the Premier, Nathan Rees, said two weeks ago.

"We transferred roughly half of our water supply each day up from Shoalhaven in the south.

"If we hadn't been transporting water from that river and we hadn't had water restrictions in place, our water supply would have been down to 7 per cent … that essentially means people are drinking mud."

Shoalhaven locals regarded the pumping policy as river theft and have been appalled at the damage caused to the environment.

Several intermediate waterways in the Southern Highlands were treated as canals and kept in constant flood that resulted in ecological damage to streams and rivers. In the Shoalhaven estuary, near Nowra, a lack of flushing increased salinity, among other problems, locals said.

Mr Costa has acknowledged that the transfers have caused significant erosion. He said a meeting last week with concerned locals contributed to his decision on the moratorium, but it was made easier by the fact that water storage for the metropolitan area was 65 per cent of capacity.

The progress of the desalination plant, which is expected to be completed by summer 2009-10, had also made a difference, he said.

"Because of this boost to dam levels, the great effort by water users of Sydney, massive recycling projects and the commissioning of the new desalination plant in summer 2009-10, I am able to take this action."

He has authorised a flow of 100 megalitres a day to ensure water levels remain high in the Wingecarribee River until the platypus breeding season is over.

But he said the long-term future of the top-up policy would be reviewed under a new metropolitan water strategy.

The director of the Total Environment Centre, Jeff Angel, said water transfers from the Shoalhaven had never been a good idea because they increased the impact of the city on the environment.

"The Shoalhaven and the intermediate rivers used as channels to get the water to Sydney need a long rest. It's unfortunate that the start of the desal plant is the trigger for this. It would be far preferable if we had built up recycling infrastructure instead," Mr Angel said.

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