State Treasurer Andrew Fraser said that on top of recovery costs, the state would receive less income because of damage to the mining sector.
Flood waters are continuing to encroach on Rockhampton, a city of 77,000.
The floods have affected about 200,000 people, and many have been evacuated.
An estimated 22 towns have been left isolated or inundated by the rising waters over an area larger than France and Germany.
'Huge cost'
There are concerns that damage could cost billions of Australian dollars to repair.
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QUEENSLAND
* North-eastern Australian state
* Largely tropical climate
* Area: 1.73 million sq km (668,000 sq mile)
* Coastal regions, including Great Barrier Reef, designated World Heritage Site
* Mining and cattle ranching important inland
Mr Fraser has had to delay a fiscal and economic review in order to account for the costs of the floods.
"In many ways, it is a disaster of biblical proportions," he told journalists in the flood-hit town of Bundaberg.
"The cost to the state will be huge - both in direct costs such as rebuilding roads, and other damaged infrastructure and providing relief payments to families - but also in lost income, while the mining, agriculture and tourism sectors recover," he said.
"Royalty forecasts are likely to be hit with freight lines cut and reports that many mines may not reach full production again for two to three months."
In some areas the waters have been receding, but around Rockhampton they are still rising.
Rockhampton Mayor Brad Carter said about 40% of the city could be affected when the Fitzroy River reaches its expected peak next week.
"We know we have prepared as best we can - most people who are expecting water to inundate their houses have evacuated," he said.
He said others who needed to evacuate would be advised to leave their homes, and those who refused could be forced to leave.
Among the areas already hit by the flooding are Emerald - a town of some 11,000 people - and two smaller towns, Theodore and Condamine, which have been completely evacuated.
Australia's Queensland faces 'biblical' flood
