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What is Coal Seam Gas Water?

Coal Seam Gas (CSG) water is water extracted from coal seams in order to release coal seam gas. CSG is a natural gas consisting primarily of methane, which is adsorbed into coal. Once produced it can be used for the same purposes and applications as conventional natural gas. CSG is liberated by reducing the hydrostatic pressure in coal seams by dewatering. The water that reaches the surface is referred to in state legislation as 'associated water'. The term 'associated water' may also be used to refer to water produced from other petroleum activities. For the purposes of this discussion paper however, the associated water related to CSG production is referred to as CSG water.

How is Coal Seam Gas water currently managed?

CSG water is currently considered a waste by-product from an industrial perspective by environmental agencies. Although, it may be approved as a water resource on a case-by-case basis depending on its salinity and its intended use.

At present, CSG water is disposed of in evaporation ponds ranging from 1-100 hectares in area. The Queensland Government however has determined that re-injection is its first preference for the disposal of CSG water. As a result, evaporation ponds are to be discontinued as a primary means for the disposal of CSG water and remediation of all ponds to occur within three years.

Beyond re-injection, a limited quantity of untreated CSG water is currently used for feeding stock, coal washing and related petroleum activities. Trails are also being conducted to develop other uses, such as treated water to augment town water supplies, as cooling/blowdown water in power stations and for irrigation and aquaculture.

The opportunities for use of CSG water should also take into account regional water supply planning and infrastructure development.