In the 1970s, two huge open-cast lignite mines were opened up south-east of Peitz to supply the Jänschwalde power station. The Jänschwalde open-cast mine is still active today and is continuously moving towards Guben.
The smaller Cottbus-Nord open-cast mine has expanded to the north-east of Cottbus. In the past, the villages of Groß Lieskow, Klein Lieskow, Tranitz and Lakoma were located here. Since the end of 2015, no more coal has been extracted from this open-cast mine. At the end of 2018, the mine began to be flooded with water from the River Spree. By the mid-2020s, the gigantic pit is to become the largest lake in Brandenburg – the Cottbus Ostsee, with a surface area of 1,900 hectares. At its deepest point the lake will be about 30 metres deep. Over the next few years, the banks will be designed to create lidos, campsites and even harbours. The eastern part of the lake with islands will later provide space for the natural environment to flourish.
Near the village of Neuendorf there is a lookout point which offers an interesting view of this unusual landscape. Several display panels provide information about the current flooding of the lake and the recultivation project.