People for the Plains appealed the August NSW Land and Environment judgement, which gave the Leewood development the green light.

Environmental Defenders Office chief executive Sue Higginson said the appeal went “as well as it could have”.

"People for the Plains made a compelling case, calling for clarity around laws and parameters of what coal seam gas exploration is, and whether it includes industrial scale water treatment facilities,” Ms Higginson said.

A Santos spokeswoman said the Leewood project was approved following a “rigorous and detailed” assessment process.

Ms Higginson said it was “a waiting game” as three judges considered the appeal.