The Viggarbach –also: Mühltaler Bach – originates out of the Blue Lake and flows through the valley with the same name in western direction and merges near Schönberg with the Sill River. The creek has a slight elliptical course with a length of 9 km.
The rapid small creek keeps its Grade A water quality in the whole course, but gets dangerous at high water or strong rain. Thanks to the fact that nearby townships are further away from the Creek, there is less danger for settlements.
The Blue Lake is the origin of the Viggarbach. It has an area size of 0,79 ha, a volume of 23.570 m³, and lies on the frontier of the Tuxer alpine area.