The State Government has announced plans to double the capacity of the Binningup desalination plant but does that secure Perth’s water future?
The plant will now produce 100 billion litres of water a year from the end of 2012, costing households an average of $50 a year.
Prior to the announcement, the Premier Colin Barnett said last month that he did not know if desalination was the answer.
“I’ve never been a great fan of desalination,” he said.
“It is a part of the water supply situation but it is energy intensive and it is expensive.
“These plants cost a billion dollars to build and they have a quantifiable lifetime.
“What I will say in defence of desalination is that the technology is always advancing and it is getting efficient and more cost effective but I don’t see us just building one desalination plant after another,” he said.
So what is the answer?
A spokeswoman for the Water Corporation says currently about 15 per cent of Perth’s water is supplied from desalination.
With the doubling of the Binningup plant output, the Water Corporation expects about 30 per cent of Perth’s water to be supplied by desalination.
In announcing the plant extension, Mr Barnett and Water Minister, Bill Marmion say the increased capacity could even supply up to half of Perth’s water needs.
“It does give medium-term water security to the people of Perth,” said Mr Barnett.
Mr Marmion added, “It will drought proof Perth”.
Situation
Even if the desalination plant supplies 30 per cent of Perth’s water needs, that still leaves 70 per cent to be met by groundwater and dams.
Perth’s dams are only at around 25 per cent capacity and since 1975, the amount of water actually received into the dams has dropped considerably.
According to the Water Corporation, between 1911 and 1975, the average inflow into Perth’s dams was 338 gigalitres.
Between 1975 and 2000 the average inflow dropped to 177 gigalitres but from 2006 to 2010 the average has plummeted to 57.7 gigalitres.
Professor Jorg Imberger from the University of Western Australia’s Centre for Water Research has welcomed the expansion of the Binningup desalination plant.
But he does not believe the state government has done enough to ensure Perth’s water supply needs.
“This desalination plant extension, while it is absolutely necessary, it’s a pity that it wasn’t coupled with increased recycling of water because there is 180 gigalitres going out in the ocean,” he said.
“Very urgently more recycling, very urgently desalination extension and very urgently you need to bring Yarragadee [aquifer] on-line.”
But Mr Barnett says Perth residents can take some comfort that it has been a wetter winter and there will be more water flowing into the dams.
Mr Marmion says the state government is considering a range of long term options for Perth’s water supply.
“These include greater use of groundwater, including continuing to investigate recycling through the groundwater replenishment trial, recycling, desalination and demand management,” he said in a statement.
“I have asked for the Department of Water to conduct a review into the longer term water supply options for Perth.”
Options
Professor Imberger says he would like to see an expert advisory committee assist in developing a long-term plan for WA, particularly as the population grows.
“It would make some sense to bring water half way down from the north and take it up from the south and generally plan it all out” he said.
The Premier has previously flagged an expensive option of bringing water down from the Kimberley to address Perth’s supply shortages.
“At least Western Australia always has in the future the option of bringing water from the north,” he said.
“We do ultimately have a solution if we need it. Some stage I do think we will need to do that.”
The Premier hopes another wet winter will buy his government some time to plan for long-term water supply but experts argue the decisions need to be made immediately.
