From the middle of the 19th century on, the onset of industrialization in the Ruhr area also triggered strong population growth. The increased demand for drinking water was covered by the Ruhr and Lippe areas, and the sewage and pit water from the mines were emptied into the Emscher.
The Emscher was forced into a straight bed and thus turned into a sewer for the Ruhr area. The formerly fish-rich river degenerated to the "Köttelbecke" of the district. Since 1992, the ecological conversion has been planned and implemented for the entire route. The wastewater is transported in huge pipes up to 40 meters underground and the clean water, renatured, guided above ground.
The Emscher conversion will take until 2020. Over a period of about 30 years, the Emschergenossenschaft invests a total of 4.5 billion euros. Since the beginning of the 1990s, around three billion euros have been spent to date. Around 290 out of 400 channel kilometers have been laid so far, just under 130 out of 350 kilometers of water courses have already been ecologically improved.