Ill, river in Vorarlberg, southeastern tributary of the Rhine, 75 km long, flows into the Rhine north of Feldkirch, average flow near Gisingen 66 m3/sec. Principal villages and towns: St. Gallenkirch (alt. 878 m), Schruns (alt. 690 m), Bludenz (alt. 588 m) and Feldkirch (alt. 458 m); major river in the southeastern part of Vorarlberg; has its source in the Vermunt and Ochsental glaciers in the Silvretta range (on the Swiss border); the Silvretta and Vermunt artificial lakes of the Ill-Werke (public electricity utilities) are located on the upper reaches of River Ill, called Ochsental Valley. River Ill runs through the Montafon Valley and the Walgau region and finally turns to the Rhine Valley near Feldkirch. Largest tributaries: Litz (Silbertal Valley), Aflenz (Klostertal Valley) and Lutz ( Grosses Walsertal Valley) in the east; Suggardinbach stream (Gargellental Valley), Alvierbach stream (Brandner Valley), Mengbach stream (Gamperdonatal Valley) and Samina in the west. Local economy is based on tourism; also textile, iron and food industries.