Bílina

The Bílina (Czech pronunciation: [ˈbiːlɪna]; German: Biela) is a river in the Czech Republic, a left tributary of the Elbe River. It flows through the Ústí nad Labem Region. It is 82.0 km (51.0 mi) long. The river flows through a densely populated area with a high concentration of industry. It is infamously known as the dirtiest Czech river, even though water quality has improved significantly in the 21st century.

Source: Wikipedia https://en.wikipedia.org/wiki/Bílina_(river)