Queensland's drought is unprecedented in its severity, and has caught everyone by surprise, says Premier Peter Beattie.
Mr Beattie said yesterday the situation in South Eastern Queensland was worse than the 1898-1903 federation drought.
"Rainfall in the region has been well below average for the past six years and in fact it is the worst 10-year period in history," he said. "It has been dry after dry, year after year, which has led to major storage deficits in our dams."
Department of Primary Industries climate technologies director Roger Stone estimated the rainfall deficit in the Wivenhoe/Somerset catchment in the past 15 years at 2500mm.
Grant Beard, from the Bureau of Meteorology's national climate centre in Melbourne, said coastal Queensland between Mackay and Brisbane was experiencing one of its driest spells on record. Rainfall from July 1999 to June this year was either the lowest seven-year period on record, or in the bottom 10 per cent.
However, the State Government's own data showed the region has experienced equally bad years in the past.
A computer simulation showed if the Wivenhoe and Somerset dams had been built early this century they would have been empty during the federation drought and close to current levels in the 1940s.
The dams would also have hit low levels in the 1920s, late 1980s and late 1990s.
Boonah Mayor and farmer John Brent doubted the worst-in-a-century label.
"This drought is not unusual. Sweeping statements are no substitute for planning," he said.
Ann Farrell, a Brisbane senior meteorologist, said the federation drought was probably worse than the present crisis.