Central Downs Irrigators chairman Johannes Roellgen, Tyunga, Pampas, said irrigators were committed to ensuring the ongoing sustainability of the Condamine Alluvium, a commitment that is soon likely to cost them hundreds of millions of dollars in uncompensated losses.

The Government is reviewing water availability in the alluvium as part its groundwater planning process, and farmers expect significant cut to their own allocations.

Irrigators now have access to 90,000 megalitres of nominal water allocation from the alluvium, but expect that to be cut by about 50 percent when the groundwater planning process is complete.

Groundwater is considered to be of greater value for irrigators than rainwater because of its permanent availability.

Every megalitre of allocated groundwater produces an estimated $1200 in gross agricultural value on the Central Downs, suggesting more than $50 million in total annual agricultural productivity will be surrendered if irrigator allocations are cut by 45,000ML as expected.

Irrigators say they are unlikely to receive any compensation for that loss in value, but understand the need to protect the resource.

"There hasn't been that much of a fight because we know how important a sustainable Condamine Alluvium is," Mr Roellgen said.

While irrigators accept sacrifices will be required to ensure the long-term productivity of the alluvium, they are perplexed by government policies that enable CSG companies to extract millions of litres of water from coal seams that are listed as part of the same allocated resource in the Great Artesian Basin Resource Operations Plan.