Santos' main environment statement on its proposed $3 billion coal seam gas project in north-west NSW lacks key data on groundwater impacts, salt disposal, air pollution and biodiversity, government agencies have found.

In their submissions, agencies such as the NSW Environmental Protection Agency and DPI Water said they did not find "critical" issues to recommend the project not succeed. They do, however, detail gaps in many aspects of the project's environmental impact statement (EIS) that hinder their ability to assess those effects.

Sarah Ciesiolka, a peanut farmer near Santos' Narrabr CSG project.

For instance, Santos presented insufficient data for the EPA to evaluate the impact on water levels of the proposed 850 CSG wells to be drilled in Stage One, the agency said.

DPI Water assessed the confidence of the groundwater model used to be "Class 1" because the groundwater pressure and level data for key formations "is limited". Such class of models "have a high level of inaccuracy which results in uncertainty of modelled impacts", DPI said in its submission.