The Blausteinsee Leisure and Recreation Area is an artificial lake north of the Eschweiler municipality in the Aachen district of North Rhine-Westphalia, Germany. Its area is around 100 hectares and depth is 46m. It was created during the regeneration of the Zukunft opencast coal mine in the Rhineland coalfield, made by flooding the pit left by the mine with water. Today, the lake is a holiday area for the surrounding towns. The surface of the lake is 129 metres above sea level and its volume is around 25 million cubic metres. The filling of the lake began in 1994. The owner of the Blausteinsee is the Blausteinsee Leisure Centre GmbH, which was founded as a support organization in 1982 by the municipalities of Aldenhoven, Alsdorf, Eschweiler, Stolberg and Würselen. The aim of this company is to create and maintain an attractive leisure and recreational area for the people of the Aachen region, along with coordination of activities on and around the lake. Location and detailed description Blausteinsee is located primarily in the municipality of Eschweiler. The only exception is the Schlangengraben stream flowing to its north, which is part of the municipality of Aldenhoven. There is a recreational area on the southern shore located in the Dürwiß district which includes an outdoor swimming pool and a place for young people to ride their bikes. The twin districts of Fronhoven and Neu-Lohnn lie on the eastern shore. The lake is surrounded by a green belt, 80–130 metres wide, with a footpath, a cycle path and a 10.3 km long rollerblading path. Altogether, the lake's recreational area consists of about 180 hectares. A diving area lies on the northwestern shore and includes a filling station and an aid for easy entry and exit. The western shoreline contains a bathing area and a beach, along with a dining area. The northern, northeastern and eastern shores are a natural reserve. History In 1981, the town of Eschweiler started working on plans for a lake in the town (the Eschweiler Sea). The Eschweiler sailing club had already been formed two years previously. In 1982, the relocation of the population of Erberich, Langendorf, Laurenzburg, Lürken, Langweiler and Obermerz to the towns of Neu-Lohn and Fronhoven began. Blaustein GmbH was founded as a local supporting organisation by the towns of Aldenhoven, Alsdorf, Eschweiler and Würselen and the name of the lake was changed to Blausteinsee. This was