On July 18, 2009, an important landslide occurred in Nachterstedt City toward to the artificial Concordia Lake, which was created, in 1994, at the place of an old coal mine, at the edge of the city. The area is located to North-East of Harz, between the cities of Aschersleben and Quedlingburg. An underground coal mine is responsible for this damage which caused the damage of a privet house and a big building. Three people were also died. The mine apparently closed in 1991 whereupon it was converted into a recreation area. The landslide was caused by the increase of the groundwater level, in the coal mine, after a heavy rain, in relation to the water level of the lake.