Lieser, River, Carinthia, northern tributary of the River Drau/Drava in upper Carinthia, 45 km long, generally very good water quality. Rises near Kleines Sonnblick (mountain peak, alt. 2,992 m) at the Salzburg border, near Gmuend (alt. 741 m) it joins the River Malta from the north-west and joins the Drau river south of Spittal an der Drau (alt. 560 m); average rate of flow of 24.3 m3/sec. The uppermost section is called Poellatal valley, from Rennweg (alt. 1,153 m) to Gmuend Katschtal Valley, from the latter onward it is called Lieser valley. Grain is cultivated up to an altitude of 1,500 m. The valley is crossed by the Tauernautobahn A 10 from Altenmarkt to Spittal an der Drau (partly along an old Roman road).