The Große Aue rises at a height of sea level (NN) as the Aue on the southern side of the Wiehen Hills in the village of Dono in the parish of Rödinghausen in North Rhine-Westphalia. After one and a half kilometres it turns north and from its confluence with the Nordbach, which joins it from the west at Schwenningdorf, is known as the Große Aue. It crosses a water gap in the Wiehen Hills, losing 40 metres of height and powering two mills, so that in the section through the Wiehen crest it has been named the Neuer Mühlbach (New Mill Stream) after the Neue Mühle (New Mill) at Schwenningdorf. Further downstream near Fiegenburg it collects a tributary from the west which drains the entire Egge valley (Eggetal), and is then known as the Mühlbach (Mill Stream), powering the mill at Gut Grollage, east of the Egge in front of the main crest of the Wiehen Hills.