Queensland’s Surat Basin has the third largest energy resource in the world — with vast coal seam gas and coal reserves — but farm groups are warning that mining areas, which are prime farm land, risk catastrophic environmental damage to food-producing areas.

Mining development is moving very quickly with 36,000 wells due to be sunk in the next few years.

A Senate inquiry into the impacts of mining in the Murray-Darling Basin heard evidence from farm and mining industry representatives in Oakey on the Darling Downs yesterday.

More than 60 individuals and groups made written submissions to the inquiry and representatives presented evidence to the committee and answered questions from the ALP, Liberal, Nationals and Green senators.

The four senators were visibly shocked at some of the evidence presented.

In one case, Queensland’s environmental watchdog, the Environmental Protection Agency, had given permission for a flooded central Queensland mine to pump contaminated water for several months into the Fitzroy Basin river system, turning the river blue and forcing towns downstream to drink bottled water for several months because the water was undrinkable.

In another case, mining company Ambre Energy, which is proposing a controversial coal mine and petrochemical plant in the rich Felton Valley farming district, formed a community liaison committee in which members were forced to sign confidentiality agreements and membership was kept secret from the community.

Farm groups told the inquiry that mining of floodplains at the headwaters of the Murray-Darling Basin threatened water supply and water quality downstream because the land, which had once been under oceans and therefore has very high subsoil salt content, would be dug up and the salt released into the waterways.

Darling Downs farmer Jeff Bidstrup said that removing soil to dig open-cut coal mines in the area would expose subsoil with 31 tonnes-per-hectare of salt, which would then leach into river systems.

He said black soil flood plains in the region should not be mined for coal seam gas either because the extraction of saline underground water would bring up an estimated 2000 tonnes of salt per day during mining for 30 years and mining companies did not have any firm plans on how they would dispose of the salt.

“With 300 years supply of export coal in Queensland, it is surely inappropriate to destroy our premium food bowl before exhausting other options for mine sites,” he said.

Bidstrup said prime land could be mapped very easily and very quickly from existing maps but this had not been done.

“Currently the Queensland government has no plan at all and they have never refused a mine on the basis of protecting prime farm land,” he said.

A Queensland Resources Council representative told the senate inquiry the mining industry had “no problem” with protection of prime agricultural land but there were no guidelines yet on what areas needed to be protected.

A spokesman for Santos gave evidence that the company had not reached a final conclusion on what to do with salt extracted during mining but was currently considering a range of options including re-injecting the salt into the coal veins.

Felton Valley farmer Rob McCreath welcomed the senators’ visit because it put the issue of the threat of mining to farmland on the national agenda.

“Australia’s population is growing, we are faced with climate change, so we really need to look after areas that produce a lot of food,” he said.

Water flowing through the Felton Valley, 30 kilometres south west of Toowoomba, flows into the Condamine River, at the headwaters of the Murray-Darling Basin. Felton Valley farmers are concerned a proposed open-cut coal mine will jeopardise bore water supplies because test drilling for coal has intersected underground aquifers, said agricultural scientist and Felton farmer Vicki Green.

The mining company also plans to build a 30-metre high levy bank beside Hodgson Creek to protect the site from flooding.

McCreath said if the levy bank was ever broken, a large amount of contaminated water would be released into the creek.

In addition, the coal resource is under a hill and removal of the hill will remove the water re-charge area of the underground aquifers in the valley, which currently supply water to 586 licensed water bores supplying domestic and stock water within 10 kilometres of the mine site.

McCreath said that at full production, the mine would need more than twice as much water as the city of Toowoomba.

He said farmers wanted the Senate committee to produce a report that called for legislation to protect prime farm land, land of high environmental importance and to protect areas with large numbers of people.

Nationals Senator John Williams said food-producing black soil country with underground aquifers, such as on the Darling Downs, made up only 3% of the world’s land mass.

In Australia, it is even more rare, making up .16% of Australia’s land mass.

Senator Williams said state and federal governments should look at protecting food-producing land to protect it from being mined or used for planting trees for carbon sinks so it could be quarantined for growing food.