The New South Wales Government has put up tenders for the monitoring of coal seam gas impacts on groundwater, but some residents say it may be too late.

The Government has called for bids from companies to set up a dozen monitoring bores across six sites in the Gloucester Basin, near Newcastle.

Earlier this year, AGL suspended work at some Gloucester sites the banned chemical BTEX turned up in flowback water from the wells.

The new monitoring bores will be set up provide more data on any potential spills or risks.

But local conservationists say such monitoring should have begun as soon as gas companies started exploring for CSG in the area.

Julie Lyford from community group Groundswell Gloucester has told the ABC that the monitoring may come too late.

“People will be shocked to know that there has been no numerical studies done in the entire valley regarding the water issues,” she said.

“Already we have significant risks, well, they're not risks any more - we have significant contamination issues now.

“We have toxic carcinogenic BTEX in the flowback water.

“But we also have fracking chemicals that have now shown up in the groundwater, such as tolcide and borate, and in the Avon River.”