News in Science

Australia's water supplies under pressure

Australia's second largest city, Melbourne, has uncomfortably low water storage levels, as most of the country faces a hot and dry summer, experts say.

Claude Piccinin, deputy executive director of the Water Services Association of Australia, delivered the update at a press briefing at the Bureau of Meteorology in Melbourne today.

"The storage level is just below 34%. That is not a comfort zone," says Piccinin. "The picture is not pretty."

Piccinin says around the same time last year Melbourne's dam storage levels were 40%.

"September and October is when Melbourne gets its best rainfall and it's been very very dry," he says.

Melbourne received only 26 millimetres of rain during September and October - the driest on record. According to Piccinin the long term average is 124 millimetres.

Piccinin says Melbourne's daily water use during 2008 has been slightly higher than last year, because of people watering gardens dried out by the weather.

With predictions of a warmer summer, Piccinin says there is a great need for additional water sources, welcoming a planned desalination plant for the city and a new pipeline to bring water from the Goulburn Valley to the north.

Other cities

Piccinin says a number of Australian cities have improved their dam storage levels, but suggests it is no time for complacency.

For example, he says, Brisbane storage levels have recovered from a low of 20% in 2007 to 42% this year. But, he adds the city's largest dam is at only 27%.

"They are certainly not out of jail at this point of time," says Piccinin.

He says the nation's capital, Canberra, has improved its storage, now at 52%, in part relying on water from the Murrumbidgee River and elsewhere.

Sydney's water supplies have improved from 59% last year to a stable 66% since February 2008 - in part this has been managed by transferring water from the Shoalhaven water system, says Piccinin.

He says Sydney's planned desalination plant puts it in a "much better position than just about every other city."

Perth has storage at 42%, while Adelaide at the end of the River Murray, has storage of 73%, relying more on drawing on the river than storage.

Darwin and Hobart, the only Australian cities without water restrictions, have storage levels of 90% and 95% respectively, says Piccinin.

He says Australians overall are using far less water than they used to thanks to water restrictions, recycled water, rainwater tanks, water efficiency measures and higher water prices.

"Some water utilities are starting to rate garden plants in the same way as washing machines," he says.

But Piccinin says water efficiency gains are being more than offset by population growth which will increase by a third in Australia's capital cities over the next 25 years.

"Between 2005 and 2030 Melbourne will have to accommodate another million people," he says.

Hotter and drier food bowl

The briefing also heard an update on the state of the Murray-Darling Basin, Australia's food bowl, and home to many sensitive environmental areas.

Bureau of Meteorology senior climatologist Dr Andrew Watkins says the basin has been suffering the results of overlapping dry periods and the second warmest seven-year period on record.

"This is the worst drought we've seen over the Murray-Darling Basin," he says. "It's very hard on the farmers."

Watkins says while the rise in temperature is consistent with climate change, it is not possible at this stage to confirm whether the reduction in rainfall is directly linked.

Dr Wendy Craik, chief executive of the Murray-Darling Basin Commission told the briefing that internationally important wetlands such as the Lower Lakes and other "icon sites" are continuing to deteriorate due to low inflows to the basin.

"There's no real relief in sight," she says. "There's very little environmental water."

Craik says only 2 gigalitres of river water will be available to maintain drought refuges and avoid loss of species.

She says water trading of hundreds of gigalitres has helped irrigators and communities survive by reducing the effect of drought by 50%.

Craik says the Commission's strategy is to continue to minimise evaporation and salinity while maximising water availability.

The media briefing was facilitated by the Australian Science Media Centre.