It's temporarily stored there and launched to the Kleiner Brombachsee via the Altmühl overpass if the water stage is exceeded. When water is low, water can be launched from the lake back into the Altmühl, but as a rule it is initially transported from the Altmühlsee through the 8.7 km lengthy Altmühl overpass, which crosses underneath the watershed in a tunnel over a distance of 2.7 km the Kleiner Brombachsee and from there into the instantly adjoining Großer Brombachsee. Source fed. Alongside the federal highway 466, which it crosses below twice after leaving the forest on a north- easterly course in direction of the eponymousmajor city of Markt Gnotzheim, it reaches it and briefly runs underneath its western tip. West of Unterwurmbach, the federal highway 466 ( B 466 ) ( Schwabach- Göppingen ), which ran by means of Unterwurmbach till 1989, forms a bypass street. Half a kilometer away, federal freeway 13( Würzburg- Ingolstadt ) to the east leads to federal freeway 2 ( Nuremberg- Augsburg ), around 20 kilometers away. The A 6 ( Heilbronn- Nuremberg ) runs around 22 kilometers north.