Impact of regional groundwater flow on the water quality of an old post-mining lake

Investigations have been carried out on a post-mining lake (Lake Senftenber g) near the town of Senftenberg, Germany, which was flooded 25 years ago. I n its close vicinity several mines have just been abandoned or will be aban doned in the next few years. A change of the local hydrologic flow system i s expected. All water levels in post-mining lakes in this area will be cont rolled to maintain a level liow enough to prevent buildings from being dama ged. The lakes and most surface waters in this area are influenced by acidi c mine drainage. Based on a regional groundwater model, geochemical mass ba lance calculations were performed. Water quality changes due to the oxidati on, hydrolysis and precipitation of metals were investigated. These calcula tions reveal a high probability of acidification for the investigated Lake Senftenberg. The surrounding post-mining lakes will reach a higher water le vel than Lake Senftenberg. Thus, after 2010, ground water from the north wi ll flow through large overburden dumps and infiltrate Lake Senftenberg. (C) 2001 Elsevier Science B.V. All rights reserved.