A decades-old irrigation scheme to reverse the big dry that has crippled farmers is making a comeback with politicians from all sides pitching it as their solution to drought.

Premier Annastacia Palaszczuk dusted off the 1930s Bradfield scheme on Wednesday, followed a day later by her opponent, Liberal National Party leader Deb Frecklington.

Neither believe the initial size of the plan to redirect water from the state's north to its west, and then through New South Wales to South Australia, would work.

But both have suggested smaller or supposedly different alternatives.

The premier says she is open to discussing a scaled-down approach with Prime Minister Scott Morrison.

Ms Frecklington says her party's version would be state-owned, create tens of thousands of jobs, drought-proof the state and create "green and clean" energy.

She has floated a rough cost estimate of $15 billion over ten years, and hasn't ruled out foreign investment or borrowing to pay for it.

The opposition leader has also suggested covering the cost with royalties.

She says these royalties would flow into state coffers after an elected LNP-government followed through on plans to open up the coal-rich Galilee Basin.

The Bradfield scheme has been talked about by politicians from across the spectrum for years.

Former Queensland premier Peter Beattie raised it in 2007, followed by federal MP Bob Katter the next year.

In February, the New South Wales Nationals said they would fund a feasibility study, and former deputy prime minister Barnaby Joyce and One Nation senator Pauline Hanson have also thrown their support behind it.

"The LNP has hardly spoken a word of it, even criticising me for raising it, but now that there's an election looming they've decided to steal the One Nation policy and run with it," Senator Hanson said on Friday.

Meanwhile, the Katter's Australian Party wants the government to give water to farmers instead of withholding it for the benefit of the environment during droughts.

Australian Associated Press