The Black Elster or Schwarze Elster is a 179-kilometre long river in eastern Germany, in the states Saxony, Brandenburg and Saxony-Anhalt, right tributary of the Elbe. Its source is in the Upper Lusatia region, near Elstra.
The Black Elster flows through the cities Kamenz, Hoyerswerda, Senftenberg, Lauchhammer, Elsterwerda, Bad Liebenwerda, Herzberg and Jessen. It flows into the river Elbe at Elster, upstream from Wittenberg.
Wikipedia https://en.wikipedia.org/wiki/Black_Elster
Coordinates 51°11'31.742" N 14°7'57.325" E