A conference this week discussed what can be done with Australia’s 50,000 disused mine sites.

The fate of Australia’s abandoned mines and the stress they place on government finances was the focus of the Life-of-Mine 2014 Conference in Brisbane.

Local, state and territory governments must all deal with the incredibly expensive and arduous task of cleaning up derelict mines.

In days past, it was the case that the Federal Government, individuals and mining companies were not held responsible for full rehabilitation when mining was over.

Luckily, these days most mining projects and companies are subject to strict regulations that include security deposits to cover clean-up if their mine goes bust.

However, these stipulations do not always cover the full extent of mining’s toxic legacy, and a huge amount of costly rehabilitation work remains.

Queensland alone has about 17,000 abandoned mines, 3,500 of which are on Crown Land and therefore under the state’s remit.

An interim report by the 2011 Queensland Flood Committee Inquiry found that the Queensland State Government’s liability for cleaning up these sites would be about $1 billion.

The Northern Territory Government’s mine rehab liability would be about as expensive.

New South Wales has over 500 derelict mines contaminating thousands of hectares of land, which cannot be used for agriculture of any kind.

The NSW Government spent just $1.6 million rehabilitating sites in the 2012 financial year and allocated $4.27 million for the next year’s mine rehabilitation under the Derelict Mines Program.

Mine rehab includes fencing, filling mine shafts, managing acid drainage, water and sediment monitoring and revegetation, among many other needs.

Ignorance can be much more expensive though, as is shown when abandoned mines are affected by extreme weather.

A clear case came in January 2013, when Cyclone Oswald caused around 20 Queensland mines to dump waste water in passing floods.

Acid and heavy metals were spilled into rivers, turning some to a lurid shade of aquamarine.

Farmers reported that birds and fish died, and the ongoing damage to food safety and farmland is difficult to tally.

Life-of-Mine 2014 ends on Friday.