Three government departments held the audits at nine mines, seven of which were in the Upper Hunter, in what is said to be the first round of broader compliance audits.

The departments found that mine practices needed to be improved in relation to suppressing and preventing dust emissions, but that there appeared to be no cause for serious alarm and some mines showed innovative practices.

The breaches ranged from an unspecified mine scheduling blasts during unsuitable windy conditions because it did not use "real time" weather information, to a mine not having a bushfire management plan and a mine not using enough water carts to minimise dust when trucks were moving coal.

In relation to coal stockpiling, the audits identified "activities under way at several mines in areas outside those approved for mining and thus not currently being regulated", which "may increase the cumulative impacts of operations".

The mines audited were Drayton, Ashton, Boggabri, Camberwell, Hunter Valley Operations, Glennies Creek, Mount Arthur Coal, Mount Owen and the Wilpinjong mine.

The audits looked at compliance with separate conditions imposed by the Department of Environment, Climate Change and Water, Industry and Investment and the Department of Planning.

A Department of Environment summary report released this month said of the breaches the Planning Department identified, 13 per cent were ranked "code orange" in a risk matrix, which was "still a significant risk of harm to the environment" but a "lower priority".

Most breaches the Environment Department identified were "code blue", which related to reporting and administratiion but were "still important to the integrity of the regulatory system".

Industry and Investment condition breaches were mostly "code yellow", a low priority.