Regional comparison of impacts to stream macroinvertebrates from active and inactive coal mine wastewater discharges, Sydney Basin, New South Wales, Australia

This study investigates macroinvertebrates from waterways receiving wastewater from coal mines in the Sydney Basin. Three of the coal mines were inactively mining oar and four actively mining oar during sampling. Macroinvertebrates were collected from each collieries receiving waterway upstream and downstream of all mine wastewater inflows. All the coal mines wastewater discharges are licensed and regulated by the New South Wales Environment Protection Authority (NSW EPA). Results of the study show that the coal mine wastewaters being discharged are having varying negative impacts to the receiving waterways aquatic ecosystem through macroinvertebrate biotic indices, despite whether mining is active or inactive. Biotic indices measured at active and inactive coal mines show that actively mined wastewaters are most likely causing less of an impact to the receiving waterways aquatic ecosystem than inactively mined wastewaters. All the waterways receiving untreated (inactively mining) wastewaters recorded statistical differences for all biotic indices when analysed between their upstream and downstream sample locations. This was in contrasted to the actively mined (treated wastewaters) with only one of the streams sampled recording statistical differences for all biotic indices. Results suggest that once mining ceases and the treatment of the coal mine wastewaters subsequently ceases the receiving waterways aquatic ecosystem are clearly more degraded. This is of great concern as once mining ceases so does the treatment of their wastewaters. It is recommended that the NSW EPA further investigate measures of treatment post coal mining at these mines to ensure further degradation of the receiving waterways ecosystem does not occur.