A cotton farm with the unassuming name of Cubbie Station is up for sale.

Ordinarily, this would merely be the subject of discussion around homestead dinner tables and in the boardrooms of corporations keen to expand their rural interests. But Cubbie is no ordinary cotton farm.

It is Australia's biggest and sits at the northern end of one of the country's most heavily debated environmental icons ? the ailing Murray-Darling river system.

Not only that, a large portion of the region's families depend on its fortunes for jobs.

Cubbie's owners want at least $450 million for the 93,000ha property, which can produce around 300,000 bales of cotton and 22,500 tonnes of wheat in a good year.

The massive cotton farm, which lies on the Culgoa River, can divert and store enough water to fill Sydney Harbour with some left over ? 538 billion litres. But it currently holds about 20 billion litres in storage.

Jones Lang LaSalle managing director Stephen Conry, the agent for the property which is out for tender, says he expects it to attract global interest.

"Cubbie is a piece of Australian rural history, as a major world producer of high quality cotton and as one of the largest singular irrigation developments within Australia," Mr Conry said.

Cubbie Station chairman Keith De Lacy says the Cubbie Group planned to reduce its debt ? which he admits are not sustainable in the long term after only one good year in seven ? and recapitalise the business once it is sold, before pursuing other opportunities in agriculture.

But behind the sales pitch lies a political football.

In 2002, then prime minister John Howard's federal cabinet foiled a plan by Queensland premier Peter Beattie to acquire the property in order to return the water back to the Murray-Darling river system in the form of "environmental flows".

This was despite Mr Beattie citing a scientific study that he said showed millions of hectares of southern Queensland was in danger of being wasted by salinity within three to five decades if action was not taken.