THE $2.5 million Grantham Floods Commission of Inquiry's commissioner Walter Sofronoff said the Wagner family had been unjustly blamed for the 2011 Lockyer Valley flood that killed 12 people.
He said there was no cover-up over the quarry's role in the flood, despite some residents' concerns.
In the report that was handed down today, Mr Sofronoff made no recommendations on how to mitigate future disasters because it was not part of the inquiry's terms of reference.
The report stated, "Quarry or no quarry, railway line or no railway line, if there is ever another sudden dump of water in the upper catchment of the Lockyer Creek of the order of that which fell on 10 January 2011, the same thing will happen again".
"It happened because there was an extraordinary amount of rain that fell into the catchment so that the land became saturated and any further rainfall wouldn't go to the ground," Mr Sofronoff said.
"It would go straight down, the water then goes straight into the creeks, the creeks then lead to Lockyer Creek, Lockyer Creek runs past Grantham, and there you are."
One of the owners of the quarry at the time of the flood, Denis Wagner, said some media outlets fed the attacks against the quarry.
Those attacks were led by Sydney shock jock Alan Jones.
Mr Wagner, in a Toowoomba press conference, said Mr Jones should hang his head in shame.
But he said the inquiry revealed what he knew - that the quarry was not to blame.
Mr Wagner said the inquiry was good in that it gave residents an opportunity to tell their stories.
Lockyer MP Ian Rickuss questioned whether the inquiry cost $2.5 million, suggesting it could have blown out to $10 million when several Queensland Government departments' work and the Wagner family's legal fees were taken into account.
He said the Lockyer Valley Regional Council's costs would have likely been about $500,000.
Mr Rickuss stopped short of condemning the decision to have another inquiry into the flood, but accused Premier Annastacia Palaszczuk of being driven by ideological groups and media personalities.
The inquiry heard from 41 witnesses, including 21 eyewitnesses, and more than 300 exhibits were tendered as evidence.
Mr Sofronoff said many people would not recover emotionally from the natural disaster.
"You know that if the crisis cuts you deeply enough you never get over it," he said.
"It was really the most shocking thing I've ever been involved in looking at in 24 years of practice."
The State Government will consider the report.
The initial Queensland Floods Commission of Inquiry cleared the Wagner family of any culpability but residents said the investigation was rushed and flawed.
Queensland Premier Annastacia Palaszczuk ordered the new inquiry after a report in The Australian claimed several inconsistencies in the initial report over the role the quarry played. - APN NEWSDESK