Yelang Lake, located in Puding County, China, is the main drinking-water source for Anshun City with a population of approximately 2.5 million. Sediment and water samples were collected from YeLang Lake and its input rivers, which flow across an abandoned lead and zinc mine. Thirteen kinds of heavy metals were analyzed in addition to conventional water quality index. The results showed that the lake water quality was good and could be used as a drinking water source after the mining activities were stopped 2 years before. However, the concentrations of heavy metals in sediments, especially Zn, Pb, Cd and As, remained at rather elevated values, posing a potential threat to the local aquatic environment. Concentrations of heavy metals in sediments increased with depth, and then decreased with peak concentrations appearing at 20-40 cm. This distribution pattern of heavy metals in sediments reflects the history of lead and zinc mining activities at the upstream of the studied lake. Regular monitoring of water quality must be strengthened to prevent environmental pollution incidents.