EMSCHER

The 'Emscher' is a relatively small river, right tributary of the Rhine, flowing through the Ruhr area in North Rhine-Westphalia in western Germany. Its total length is 84km, its average discharge near the mouth into the lower Rhine river is 16 m³/s (cubic metres per second).
The 'Emscher' has its source in Holzwickede, east of the city of Dortmund and then flows west through the Ruhr area. Towns along the Emscher include Dortmund, Castrop-Rauxel, Herne, Gelsenkirchen, Essen, Bottrop, Oberhausen and Dinslaken, where it flows into the Rhine.
Being in the geographical centre of this vast industrial area of 5 million inhabitants, the river is biologically dead, as it was already transformed into an '''open waste water canal''' in the end of the 19th century. Due to the downward movements of the soil as a consequence of the mining industry, the natural course of the river could not be maintained; its mouth into the Rhine had to be relocated to the north twice throughout the decades. A huge modern sewage treatment plant at its mouth ensures that the water of the Emscher enters the Rhine in an acceptable quality.
Since the beginning of the 1990s, a huge '''renaturation project''' for the 'Emscher' river has been established. For the sewage, a large subterranean pipe is currently being constructed all along the course of the river. A first section of the river is currently being subject to renaturation in the city of Dortmund. The total project comprises costs of several billion Euros and is to be finished by the year 2014.
Sources:
www.emschergenossenschaft.de