The Ötschergräben are a gorge in the municipality of Mitterbach on Erlaufsee in the state of Lower Austria. The Ötschergräben were formed by Ötscherbach, a tributary of the Erlauf and have a length of about 5,500 meters (the veil between the Schleierfall and the estuary of the Ötscherbaches in the Erlauf). The trenches are covered by the Ötscher in the north and the Gemeindealpe in the south, they lie in the nature reserve Ötscher-Tormäuer. About the canyon walls pour two tributaries as waterfall into the main trench (Mirafall and Schleierfall), in the dry summer months, sometimes they dry up.
(Source: http://de.wikipedia.org/wiki/%C3%96tschergr%C3%A4ben (German))