Conservationists have failed in their bid to stop a coal seam gas wastewater treatment project near the Pilliga State Forest.

Gas giant Santos has plans to process and treat wastewater from its coal seam gas at the Leewood facility near Narrabri, which is on land it already owns.

The company says it will be treating water for agricultural production from existing storage ponds onsite.

Environmental group People for the Plains attempted to poke holes in Santos’ plans for the Leewood facility, which were allegedly approved without an environmental impact statement.

People for the Plains claimed in court that Santos was operating well outside its approved activities, performing full-scale gas production and agricultural activity on a licence that only allowed it to explore for petroleum.

The Land and Environment Court has this week ruled that Santos was operating within the law, dismissing the case.

Justice Timothy Moore said the Leewood plant was part of the gas exploration project, and did not need its own approval.

Justice Moore described the project as “properly characterised as being for the purpose of the activity of petroleum exploration”.

He said there was no need for development consent because the facility did not prohibit the crop irrigation.

Santos welcomed the ruling, saying the plant was not a threat.

“This reverse osmosis plant is similar to those used across the world,” the company said in a statement.

“It will be used to treat salty ground water produced by Santos' exploration and appraisal operations to a very high standard.”