New National Pollutant Inventory data shows that either some industries have seen radical changes in their emissions or the scheme's quality control is poor.
A Glencore zinc and lead mine plagued by smouldering rock dumps releasing plumes of sulphur dioxide and contaminated water seepages has revealed new management plans.
Wastewater businesses say NSW's load-based licensing scheme should focus more on nutrient trades and offsets, while mining companies say they should continue to be exempt.
The National Pollutant Inventory is to be reviewed and could soon undergo significant changes, including the removal of about a third of reporting facilities.