Sir Leo Hielscher, who served as under treasurer to 15 Queensland treasurers from both sides of politics, said debt was a "worry" and there seemed to be no plan to pay it off.

Treasurer Jackie Trad's first budget revealed the state's total borrowings would reach $83.09 billion by 2021-22.

"Sorry kids, sorry grandkids," Sir Leo said, delivering the annual Sir Thomas McIlwraith Lecture, organised by conservative think-tank, the Australian Institute for Progress.

"The interest cost even at today's relatively low interest rate would be fairly close to $2500 million per annum," he said.

"We should be trying desperately to cap and reduce the size of this millstone.

"If we attack and then try to eliminate the debt over say 20 years - and that's a long time - the cost to the budget would be in the vicinity of $5.5 billion per annum ... It would pay for our Cross River Rail project in year one."

Sir Leo said the budget was like the household budget: "If you do not have the cash, you should not spend it.

"You don't borrow to pay for the groceries or other lifestyle day to day outgoings," he said.

Asked about asset sales - an unpalatable topic in Queensland politics in recent years - Sir Leo said schools, hospitals and police stations which were needed for social obligations should not be sold.

"But when the asset gets into the commercial side, for example, railways and ports and that sort of thing, unless you need them, you still need the port authority to facilitate your further development of industry behind it, they're certainly available for, to my view, for privatisation," he said.

Sir Leo, 91, said "we need Adani or other project of similar size".

But he questioned whether Queenslanders were getting as much as they should out of the project.

"For Adani, we would have owned the railway line and its rollingstock and he would have paid for it," he said.

"You see now, Adani owns the line and he asks us to front up with $1 billion [from the Northern Australian Infrastructure Facility]."

Sir Leo expressed support for a new coal-fired power station in Queensland.

"What we need right now is a clean coal-fired power station to maximise our natural strength," he said.

"We have plenty of coal and coal-fired power generation produces one of the cheapest electricity."

Sir Leo, after whom the two Gateway Bridges were renamed in 2010 under the Bligh government, said the state should look at a Snowy Mountains-type authority to harvest and bring north Queensland water through the Great Dividing Range.

"This would firstly irrigate hundreds of square miles of fertile black soil west of Charters Towers and then as stage two carry on to the Warrego River, the northernmost arm of the Darling, the Murray-Darling system benefits and Adelaide gets a drink," he said.

"The scheme proposed is based in part on the old Bradfield scheme from the '30s that failed mostly because of lack of funding - It should be a tremendous boost to our economy."

Sir Leo, also the former Queensland Treasury Corporation chair, said he also supported nuclear power generation.

"I see a place for coal, hydro and nuclear, yes," he said.

When Sr Leo retired in 2010, then premier Anna Bligh said he had made an "unrivalled contribution to Queensland" since he took a job with the state audit office in 1942, aged 15.

Ms Bligh said Sir Leo had established Gladstone as an industrial and resources hub, negotiated key contracts with mining companies to secure royalties for taxpayers and facilitated the state's casino industry, two coal terminals and established the QTC.

Attendees at the dinner including former premier Campbell Newman, former treasurers Keith DeLacy, Joan Sheldon and Andrew Fraser, Katter's Australian Party MPs Bob Katter and Robbie Katter, and LNP MP David Crisafulli.