"When we first came down here, we had wetlands in front of us," Owen told Reuters as he looks out at a sandbank between his property and the river, now 200 metres (220 yards) away. "Now you can just walk up and across the sand. It's just filled up."

It is an undignified end to an once-mighty river system, which is now battling rising salinity, decreased water flows, the after-effects of drought and demands of irrigators.

The river is a lifeline in a parched continent, feeding water from the sub-tropical north down the Darling River, and from the eastern snow fields, where the Murray starts 2,500 km (1,550 miles) from its final destination.

The Murray-Darling basin is also the nation's food bowl, accounting for 41 percent of the value of Australia's agricultural produce.

But so dire is the plight of the dwindling, polluted river system, the national government decided restoring it is a key environmental goal.

One aim is to try to increase the amount of water in the river to stop the mouth closing over.

Near its end, the Murray flows into two massive, shallow lakes before snaking around Hindmarsh Island on its way to the sea, at a place with a reputation as a notoriously dangerous stretch of water.

From his shack, Owen can see two dredgers that have operated without a break for three years to clear away three million cubic metres (3.9 million cubic yards) of sand so the Murray's waters can make it to the ocean.

Without the dredging, or a significant increase in water flows, the water merely fills the low-lying lakes instead of being flushed out to sea.

AUSTRALIA'S MISSISSIPPI

Adelaide, the capital of South Australia state, draws 40 percent of its water from the river. The government says supplies from the Murray could be unfit to drink within 20 years for the city of about one million.

"Doing nothing is not an option," said Wendy Craik, chief executive of the Murray-Darling Basin Commission, which manages the river on behalf of four state governments, the national government, farmers and environmentalists.

The Murray-Darling catchment covers 1.06 million sq km - 15 percent of Australia's landmass and an area the size of France and Spain combined - and plays a crucial role in supporting Australia's economy and rural life. It also has a big place in the nation's history.

Throughout the 19th and early 20th century, until rail took over, paddle steamers plied the river, transporting wool, wheat and goods from town to town, prompting writer Mark Twain in the 1880s to liken the river to America's Mississippi.

During that period, farmers used the river water to irrigate crops, turning vast areas of arid lands into lush fields.

But so much has been taken out and so many areas stripped of trees that river flows are falling and salinity rising.

One company is producing gourmet River Murray salt flakes, reclaimed from what is supposed to be a freshwater river.

OLD MAN RIVER

Despite its size, the volume of water in the river is a fraction of some other major world rivers such as the Nile or the Amazon.

In an average year, 13,000 gigalitres of Murray water flows to the sea. One gigalitre is 1,000 million litres.

But after four years of drought, outflows are now down to an annual 5,000 gigalitres.

That might seem a lot of water, but it hardly compares to the 5.5 million gigalitres a year from the Amazon and 1 million gigalitres for the Yangtze.

Another problem is that the Murray is a slow and lazy river. Rainfall in the upper reaches of the Darling can take three months to make it to Goolwa, so it takes a long time for the river to flush out all the impurities.