Shortly after the river crosses the border to Polish Niedamirów and runs northwestwards through the Jelenia Góra valley of the Western Sudetes to the dam of Pilchowice and downhill into the plains of Lower Silesia, passing the towns of Jelenia Góra, Bolesławiec, Szprotawa, and Żagań, where the parallel Kwisa river joins it.

Upon Gero's death in 965, the river was the designated eastern border of the newly created March of Lusatia in the Holy Roman Empire.

During the Potsdam Conference in 1945, the Western Allies briefly advocated a Polish-German border along the Oder, Bóbr and Kwisa rivers, but were rejected by Joseph Stalin, who had already committed himself to the Oder-Neisse line.

The Pilchowice Dam (Polish: Jezioro Pilchowickie, German: Talsperre Mauer) was built from 1904 to 1912 in the northern Krkonoše range near Jelenia Góra.

Equipped with Francis turbines manufactured by Voith and Siemens-Schuckert and AEG generators, the hydroelectric plant supplies about 20,000,000 kWh a year, with a power rating of 7,585 kW.