Pollution of wetlands adjacent to Adani's main coal export port in Queensland is proof the Indian-owned company can't be trusted to operate a much larger operation should the Galilee Basin ever be opened up to mines, environmental groups said.

The Queensland government on Wednesday released the results of its preliminary study of damage to the Caley Valley Wetlands from coal fines washed into the area when Cyclone Debbie hammered the coast in late March.

Satellite images of the Abbot Point coal terminal and neighbouring wetlands. Before Cyclone Debbie, on the left, and post-cyclone, right.

The miner is also contesting fines of about $12,000 issued by the government for unauthorised releases of water into the nearby ocean that were eight times the temporarily elevated pollution limits of 100 milligrams of suspended solids per litre.

The state's Department of Environment Heritage Protection found the Abbot Point Bulk Coal port had not exceeded the 100mg limit in the wetlands themselves, and there appeared to have been "no widespread impacts".