The former owners of the Lady Annie mine have been fined for an uncontrolled contaminated water release in 2009.
CopperCo has been fined half a million dollars after it pled guilty to causing environmental harm, NineMSN has reported.
The miner initially pled guilty to the release in December last year.
According to the Department of Environment and Resources (DERM), during the 2009 wet season the company had an uncontrolled release of contaminated water into stormwater ponds and surrounding creeks.
It added that it was the most hazardous in Queensland’s history.
"The contamination extended for 52 kilometres and was highly toxic, killing freshwater crabs and fish," DERM assistant director general Dean Ellwood said.
"DERM also received calls from downstream landholders expressing concern that poor water quality within Saga and Inca Creeks could harm livestock."
DERM stated that CopperCo had already spent over $8 million cleaning up and rehabilitating the site 120km northwest of Mount Isa.
While the mine had planned to employ 150 workers and produce 19,000 to 25,000 tonnes a year, CopperCo sold it following the floods.
At the time CopperCo receivers Deloitte said the floods had "exceeded the design capacity of the site stormwater ponds".
Deloitte said site remediation had commenced immediately after the floods occurred.
The miner was forced to sell Lady Annie to fund the clean up.
Earlier this week, DERM also investigated the Baal Gammon copper mine after reported contamination of nearby waterways.
However, the high concentrations of copper in the nearby Jamie Creek were linked to historical activities in the region.