Ager (river)

The Ager is a river in Upper Austria. It is the discharge of Lake Attersee and, after a course of around 34 km, flows into the Traun from the left in the north-east, between Lambach and Stadl-Paura. The Ager drains the entire north-western Salzkammergut region. Its catchment area covers around 1,260 km². It flows through the northern Alpine foreland.

The name Ager is derived from the Celtic word Agria. The root *ag- means to flow, to lead, which is a reference to the river’s originally strong current. The Ager flows out of Lake Attersee at its north-eastern end, between Schörfling and Seewalchen, and then flows northwards through Lenzing an der Ager. From Timelkam, it turns eastwards and takes in the Vöckla at Vöcklabruck. It continues north-eastwards, past Regau, Attnang-Puchheim and Schwanenstadt, until it flows into the Traun as the boundary river between the municipalities of Stadl-Paura and Lambach.

By far the most significant tributary is the Vöckla, which flows into the Ager at Vöcklabruck. It drains more than 35 per cent of the Ager catchment area. Further tributaries, further downstream, include the Dürre Aurach near Preising, the Aurach near Wankham, the Ottnanger Redlbach just before Schwanenstadt and the Staiger Bach near Schwanenstadt. Via Lake Attersee, the Ager also drains Lake Mondsee, Lake Irrsee and Lake Fuschlsee, each of which is connected by relatively short rivers.

The Ager was formed at the end of the Würm glaciation, when the massive Eastern Alpine glaciers began to melt. Lake Attersee is a typical glacial terminal lake, as are Lake Mondsee and Lake Irrsee. However, these drain in the opposite direction, towards the south into Lake Attersee, because this transverse breach formed before the lakes could break through to the north, as is also the case with Lake Fuschlsee, which flows through the Thalgau glacial trough, which was formed at the confluence of the Traun Glacier and the Salzach Glacier. The Ager valley itself lies within the Alpine foreland and forms the Vöckla-Agertal valley, which runs eastwards across the foothills of the Alps. This is surrounded by the Ager-Traun terrace

Flows through: Austria.

River data from Wikidata (CC0); lengths normalised to a common unit.