The Wesenitz (Wjazońca in Upper Sorbian language) is a river in Saxony, Germany, a right tributary of the Elbe.

The castle's fame originates from the period 1716 until 1765 when Augustus II the Strong imprisoned there his mistress Countess of Cosel.

Beginning with the inauguration of Johann V. of Weißenbach in 1476, the Bishops of Meißen until 1559 and later the prince-electors of Saxony performed fish farming of carps in two ponds between Goldbach and Kleindrebnitz respectively in Bischofswerda, which were fed with Wesenitz water.

Down from Helmsdorf, the river Wesenitz is protected according to the Habitats Directive,[4] referring to the appearance of European bullhead and common minnow.

Since 1969, a migration from the river system of Schwarze Elster is reported at Großharthau respectively Bischofswerda and is noticed in traffic victims at crossing points over the B6.