The Ötztaler Ache is a river in the district of Imst , Tyrol state of Austria. It is a right tributary of the Inn. It flows through the Ötztal valley, a southern branch the Inntal . Including its source rivers Venter Ache and Rofenache, it is 66.5 kilometres (41.3 mi) long. The Rofenache is the runoff of the Hintereisferner , a glacier at the foot of the Weißkugel , Ötztal Alps . At Vent, near Sölden , it takes up the Niedertalbach and its name changes to Venter Ache.