Impact of a coal mine waste discharge on water quality and aquatic ecosystems in the Blue Mountains World Heritage area

Disposal of coal mine wastewater to the headwaters of a high conservation value waterway caused water pollution and ecological degradation of a World Heritage listed upland river. Below the mine, macroinvertebrate family richness decreased by 65% and abundance by 90%. Upstream of the waste discharge had very low electrical conductivity (EC) of 30 μS/cm and pH was acidic (5.6) in contrast to that below the mine which showed EC 11 times higher (342 μS/cm) and a shift in pH to 7.2. The concentration of zinc below the mine was 101.5 μg/L and while below the permitted discharge level of 2500 μg/L as set in the environmental protection license (EPL), was 10 times greater than the recommended ANZECC guidelines for aquatic ecosystems. Nickel is not regulated under the mine EPL yet a concentration of more than double the recommended guideline was reported. The mine discharge also increased water temperature in the Wollangambe River by more than 2.5° C. The data clearly points to a need to review both the operation of the mine and the enabling regulatory system that currently allows pollution of zinc 200 times greater than recommended by the ANZECC guideline and generally does not adequately consider the impacts of the mine on the downstream National Park and World Heritage listed waterways.