By integrating the chemical, toxicological and ecological data, the impact of heavy metal pollution on the Le An River was assessed. The results showed that the water and sediment pollution has affected the aquatic ecosystem due to discharges from Dexing copper mines and mines along the Jishui River. The ecological deterioration between the Dexing copper mine and the converges with the Jishui River could be attributed to acid drainage instead of extremely high content of metals in the sediment (non-bioavailable), while that between the Jishui River and downstrem 34 km could be attributed to multi-metal contamination. Sediment pollution associated with the moderate biological and ecological deterioration prevails in downstream of the river as far as the delta area of the lake.