MINE WATER MANAGEMENT AT THE CATCHMENT SCALE: CASE STUDIES FROM NORTH-EAST ENGLAND

Recent implementation of the EU Water Framework Directive necessitates addressing water quality issues at the catchment scale. In this study, contaminant loading of all point discharges have been measured, establishing the overall impact of mine waters within the catchments, and allowing the derivation of contributions of diffuse mine water pollution to these totals. The results of two ongoing case studies of mine-impacted river catchments in the north-east of England are presented. The Allen catchment, Northumberland, is impacted by discharges from abandoned Pb/Zn mines with up to 6 mg/l Zn and 0.2 mg/l Pb, which significantly exceed European ecotoxicological standards by up to a factor of 75 and 20 respectively. The Gaunless catchment, County Durham, receives uncontrolled discharges of coal mine waters with up to 8 mg/l Fe. Preliminary findings show that during both low and high flow conditions diffuse iron pollution contributes significantly to in-stream iron loadings. Probable pathways include direct groundwater input and remobilisation due to scouring of streambed sediments.