A SCIENTIFIC report to be released today confirms that Queensland's largest freshwater aquifer, the Condamine Alluvium, is at direct risk of being drained as a result of coal seam gas production on the Darling Downs.
The Condamine Alluvium is one of the most important freshwater aquifers in the State, relied upon as a primary source of water by several Darling Downs townships and an irrigation industry that generates more than $50 million of agricultural production every year.
However, its long-term future is being placed at direct risk by the expanding presence of the coal seam gas industry on the Darling Downs, according to a new report by independent hydrogeologist John Hillier.
The report, released at the Rural Press Club of Queensland's Ag Show breakfast in Toowoomba this morning, confirms that the Condamine Alluvium is hydraulically connected to the Walloon Coal Measures, which are currently being dewatered by energy companies for coal seam gas (CSG) production.
Coal seam gas extraction requires the removal of large volumes of water from coal seams to release trapped gases.
CSG companies have long insisted that the coal seams they target are confined and separated from adjacent freshwater aquifers by thick layers of impermeable rock.
However, the results of Mr Hillier's analysis of monitoring bores and existing groundwater science confirms that CSG activities are placing at least one significant freshwater aquifer at serious risk of rapid and long-term damage.
Mr Hillier's report warns that as water levels in the Walloon Coal Measures decline as a result of CSG production, a reverse gradient will be created that will cause freshwaters from the Condamine Alluvium to drain into the largely saline Walloon Coal Measures.
Mr Hillier stresses that insufficient data exists to quantify the extent to which freshwater will flow into the coal measures, but acknowledges that the potential for significant losses exists.
The findings will be used by Condamine Alluvium irrigators to support calls for a moratorium on all future CSG developments on the Darling Downs until further research into possible impacts is conducted.
Mr Hillier is a semi-retired former Department of Natural Resources scientist who has worked on Queensland groundwater issues for more than 45 years.
He was commissioned to research the possible impacts of CSG activities on the Condamine Alluvium by the Central Downs Irrigators association, which has been concerned driven by its concern about the lack of existing scientific data surrounding possible impacts of existing CSG activities in the Walloon Coal Measures on freshwater aquifers.
The Queensland Government's policies on CSG impacts are focused largely on dealing with impacts after the event, anchored on its legislation which requires energy companies to "make good" any damage caused.
However, landholders are not confident that physcial damage to freshwater aquifers or loss or water can be fixed in reality and want to see policies focused on preventing damage before it can occur.
The findings of Mr Hillier's report strengthen the case for a moratorium on new CSG developments on the Darling Downs until extensive independent research into CSG impacts on groundwater reserves is conducted.
Central Downs Irrigators are calling on the Queensland Government to fund such research, and believe it should be conducted in conjunction with an independent party such as the Toowoomba based University of Southern Queensland.
The report makes it harder for the Queensland Government to ignore long running landholder concerns over mining impacts to the Condamine Alluvium.
The Government has already approved large numbers of CSG wells in the Walloon Coal Measures, including an estimated 150 that are operating in the Grassdale area alone.
The study supports calls for further research to be conducted before any future CSG development decisions are made.
"Because of the very real likelihood of movement of groundwater from the alluvium to the Coal Measures, more data is required to allow the calculation of the volumes that could be involved," he states in the report.
Mr Hillier told Queensland Country Life this week that he believed irrigators' calls for a moratorium were reasonable.
"Where there is likely to be interaction with the alluvial water, I think it (a moratorium) is a reasonable call," Mr Hillier said.
"I think it would be derelict it if was allowed to go ahead without knowing more about that connectivity.
"If it impacts are found to very minimal then okay, but we need that further study."
He said the slow rate of groundwater movement also created concerns.
"What I consider to be a big problem is the time factor, because it could be 10-20 years before the effects (of CSG water extraction in the Walloons) is really felt, but by that time the CSG companies may be gone and the damage will be there."
A lot was known about how water moved horizontally through the sandstone layers of the Great Artesian Basin, but not vertically Mr Hillier said.
"As we reduce the pressure in one particular bed, we don't really know how much water is going to move upwards, because it is very difficult to measure."
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