the first inter-municipal project in the Aachen region. The name of the lake comes from the old district of Am blauen Stein north of Dürwiß, a 17th or 18th-century wayside cross on the road between Dürwiß and Fronhoven, as it appears in old maps. After the last of the 530 million tons of brown coal was mined from the Zukunft-West mine in 1987, regeneration began. In early 1994, the last machinery was removed from the mine. The former mines of Zukunft and Zukunft-West were around 23 km². At the same time the access road was renamed as Zum Blausteinsee. On October 5, 1994, the filling of the Blausteinsee began. The fountain was in the middle of the lake, around 500m from the shore, using around 210 liters of water per second, and reaching a height of 40m. Around 6.7 million m³ of water flowed into the lake per year, and, to start off with at least, 75 million m³ were needed because up to 50 million m³ of water either sunk into the ground or evaporated. In August 1997, the Verband der wassersporttreibenden Vereine Blausteinsee 1997 e. V. was founded. This was a follow-up to the Interessengemeinschaft Blausteinsee which was created in 1982. On August 12, 2000, the Blausteinsee was officially opened and a temporary container village was set up. In 2002, the Eschweiler sailing club and the Alsdorf sailing club constructed their own dock. Since August 2003 a private security company has been employed to patrol the area to prevent wild barbecuing, swimming and the trespassing of nature reserves. In August 2004 a part of the lake was made accessible for swimming and in 2005 the lake reached its final area of around 100 hectares and a maximum depth of 46m. A large erratic boulder on the western shore serves as a memorial to the initial filling and opening of the lake. Watersport The Blausteinsee very quickly developed into an attraction for sports enthusiasts. On the western shore, there is a diving area. Because of the sandy lakebed, the visibility depends on the number of divers but usually ranges between 1-7m. Below 25m the visibility is especially good. Many attractions have been sunk into the lake, such as a car, a wrecked dinghy, a statue of an angel and trees. The Eschweiler Diving Club has produced an underwater map showing them all. The lake is also used for canoeing,