The EPA has issued Santos two legally binding pollution reduction programs (PRPs) requiring the company to improve its groundwater monitoring and verify the operation of vents and flow lines used within the Narrabri Gas field.

"We will be monitoring the implementation of the PRPs to ensure the company is meeting its obligations,” EPA chief environmental regulator Mark Gifford said.

The incidents

In May 2013, Santos notified the government that groundwater monitoring had detected slightly elevated levels of salinity and heavy metals in the vicinity of its Tintsfield holding ponds.

Having "thoroughly investigated" the leak, which involved independent sampling, site inspections and analyses of all available data relating to the ponds and associated groundwater monitoring data, the EPA concluded that there was "insufficient evidence" to determine if the changes detected were the result of leaks from the ponds or from natural factors.

Additionally, the EPA did not detect any impacts to neighbouring stock and domestic bores.

The second incident occurred in January this year, when produced water was emitted from a high point vent on Santos' Dewhurst Southern Water Flow Line.

After receiving a report from the community, the EPA undertook an investigation but found that Santos had not breached its environment protection or the Protection of the Environment Operations Act.

However, the EPA acknowledged that such incidents needed to be prevented from occurring in the first place.

“In addition to the PRPs the EPA is impressing upon the company the importance of open and timely communication with the local community, regardless of the size or impact of any incident," Gifford said.

“CSG is a highly emotive issue within local communities around the area. Prompt communication about an incident will assist the community’s understanding of the activities and foster stronger relationships."