1. Within the Greater Blue Mountains World Heritage area, the Wollongambe River receives coal mine wastewater discharge from Clarence Colliery. Degradation of water quality and river ecology have been recorded in past research. Since these studies, the NSW EPA have required the mine to reduce levels of contaminants such as nickel and zinc within its wastewater discharge. Our current research has quantified improvements in water quality and recovery of river ecology.
2. Water and macroinvertebrate samples were collected along 20km of the Wollongambe River. To quantify water quality and river ecology, measures of salinity, various metals such as nickel, zinc, as well as total abundance and richness of macroinvertebrate families were collected.
3. Improvements to water quality have been quantified in the Wollongambe River 20km past the wastewater discharge, with levels of contaminants in the water column reducing. This includes zinc (50.2 to 11.3 μg/L), nickel (41.2 to 8.2 μg/L), and salinity (246.3 to 143.5 μs/cm). River ecology has improved 20km downstream, with macroinvertebrate total abundance increasing (10.7 to 87), and total richness (4.8 to 13.8). Pollution sensitive EPT families (caddisfly, stonefly, and mayfly) are recovering, with total abundance increasing from 5.9 to 17.2.
4. Improvements in the environmental licencing of coal mine wastewater discharges can promote the recovery of water quality and river ecology in polluted streams, as is seen in the Wollongambe River. Licences that include discharge limits on contaminants reflecting the ANZECC guidelines for ecosystem protection is a step towards more effective stream management.