The paucity of independent monitoring of waste water from coal mines in NSW is leaving communities exposed to decades of pollution, long after mining operations have ceased, Ian Wright, a leading water ecologist, said.

Dr Wright, a senior lecturer at Western Sydney University, found discharges from the Berrima Coal mine, which owner Boral closed after more than a century of operations in 2013, had high concentrations of manganese, zinc and nickel that are hazardous to aquatic ecosystems.

Downstream of the Berrima Coal mine. Credit:Ian Wright

"The impact on the Wingecarribee River biodiversity down-stream of the [Berrima] mine is greater than has been observed in mine drainage from any other Australian coal mine and is very high on an international comparison," Dr Wright said in a submission about the proposed Hume Coal mine for the Berrima region.

Dr Wright told Fairfax Media that contaminants had at least trebled since the mine's closure. Similar post-closure pollution has been evident from other mines, such as the Canyon Colliery in the Grose Valley.