The regulation and impact of eight Australian coal mine waste water discharges on downstream river water quality : a regional comparison of active versus closed mines

Water quality of rivers that received coal mine wastes from four active and three closed mines were investigated, focusing on ecologically hazardous pollutants. Zinc and nickel concentrations were highest downstream of two closed mines, particularly from the Canyon mine that closed 20 years earlier. Coal mine wastes increased nickel concentrations in waterways by an average of 25 times. The average concentration of zinc increased below mines waste discharges from 8.6 µg/L (upstream) to 83.4 µg/L (downstream). All coal mine discharges increased river salinity. Salinity increased by more than 6 times (upstream mean 101.4–741.7 µS/cm downstream). This study provides a reminder that water pollution from coal mines is a major environmental issue for both active and closed mines. The study highlights the need for more stringent and consistent environmental regulation for all mines, including key hazardous pollutants from wastes emerging from both active and closed mines.