The Enz River is 112 kilometers long and is a tributary of the Neckar, which in turn flows into the Rhine at Mannheim.
For most of its length (92 kilometers) the Nagold is a pleasant and picturesque river, flowing as it does through the Black Forest and passing for instance through the town of Calw, where the author Hermann Hesse was born.
In the city of Pforzheim, however, the Nagold was for many decades a dead, unsightly, polluted river, presumably because of the mines and factories that used to operate here. This has changed only in the 21st century with the advent of the city’s re-naturalizing program starting in 2001.
This display case near the river has before-and-after photos showing how the Nagold has been cleaned up and changed.
My photos in this post are from 2007. I revised the text in 2021.