Hume Weir, the largest dam on the River Murray, about 289 miles (465 kilometers) southwest of Sydney, is at 2 percent capacity, as shown in this February 23, 2007, photo.

As a result, trees once submerged are again visible. Many of the 50,000 farms that depend on River Murray to irrigate crops have no water allocation this year.

In November 2006, a United Nations panel on climate change predicted the annual flow into the Murray-Darling basin is likely to fall 10 to 25 percent by 2050.

The Commonwealth Scientific and Industrial Research Organization has also forecast that on the east coast, rainfall could drop 40 percent by 2070, and that temperatures will rise about seven degrees.

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