»The Emscher – black river evermore« was the title of an essay written by Gunther Annen, former manager of the Emschergenossenschaft and Lippeverband waterboard. Published in 1987 in the journal »Forum Städte-Hygiene« (Forum for Urban Hygiene), Annen describes how the Emscher might be restored to an odour-free river. The solution he suggests is to use the biological clarification plant in Dortmund-Deusen. By the same token, however, he points out that by constructing preliminary treatment works we should not delude ourselves into thinking that the Emscher »could be transformed into a river with clear water. It will look better than it does now but it will still be murky.« And, as Annen added, nor could fish be expected to thrive in the former »dung stream«.
But things turned out differently. When in the late 1980s the risk of further land subsidence abated following the northward relocation of coal mining, the idea of constructing an underground wastewater canal was realised. So in the early 1990s, the second transition of the Emscher got underway. Since then, in a mammoth process, little by little the river and all its tributaries have been emptied of wastewater and then stripped of their concrete lining, restoring them to a close-to-natural condition.