http://theconversation.com/coal-seam-gas-water-leaks-could-be-a-problem-for-decades-24718
The type of water that resulted in contamination in this case (called “produced” or “co-produced” water) is generated in large quantities by all CSG wells, and it is usually of poor quality, containing potentially harmful levels of salt, radionuclides, metals and other contaminants. It appears that in this case such water was inappropriately stored in a leaky dam, allowing it to infiltrate and migrate into the underlying aquifer.
A 2011 study in the Queensland Murray-Darling basin projected that the amounts of additional salt brought to the surface by CSG wastewater were of similar quantity to all combined salts added from conventional groundwater irrigation and natural sources. If all this salt was allowed into waterways, it would effectively double the amount of salt entering the landscape.
Managing produced water and the salts and contaminants dissolved in it is therefore major issue for the CSG industry. It can be treated and reused for irrigation or industry, re-injected underground, or released into waterways following treatment. Treating CSG wastewater usually involves reverse osmosis, which produces “clean” water, but also concentrates contaminants in brine, which requires safe disposal. Some contaminants (such as boron) are hard to remove and are retained in the treated product water. In some cases methane can also remain in water after it leaves the treatment plant, adding to concerns over fugitive emissions.