Coal mining has played an important social and economic role in Australia since mining commenced in 1860. Early coal mining activities extending to the mid mid-20^th century had few environmental protections despite an understanding of acid mine drainage and its impact on waterways. Even with the advent of environmental legislation and pollution licencing introduced in the 1970’s many active and closed mines have inadequate environmental controls. Regulation of coal mines has been focused on the point of discharge of a selected suite of contaminants. Naturally acidic streams, common in the Sydney basin, the discharge of buffered alkaline mine water designed to meet environmental pollution licence pH limits and metal concentrations, has resulted in compliant but environmentally inadequate discharges. Remobilisation of metal contaminants is occurring downstream of many current and former coal mines. This creates both longitudinal and temporal environmental problems. The impacts of coal mines on water chemistry and quality are being reported far beyond the discharge licence, arguably beyond the remit of the environmental regulator. We highlight through a number of case studies the current and emerging environmental issues on stream health directly related to mining operations and the inadequacy of the regulatory frameworks within the Greater Sydney Basin. While this may be positioned as a critique of current mining and regulatory practice, it is primarily designed to be a forewarning of adverse environmental legacy issues if not managed adequately as part of their initial project planning, operational, environmental pollution licencing, and eventual mine closure.