Aursund

Aursunden or Aursund is a lake in the municipality of Røros in Trøndelag county, Norway. The village of Brekken lies along the eastern shore and the village of Glåmos lies along the western shore.

There are several inflows to the 46 km2 lake including the lakes Rien, Riasten, and Bolagen. The outflow is regulated by a hydropower dam through which water passes into the river Glomma. The lake is about 22 km long and about 5 km wide. The deepest part of the lake reaches a depth of 52 m.

Aursunden is often cited as the source of the river Glomma, the longest and largest river in Norway. The actual headwaters are near Aursunden near the start of the Glommadal valley. The locals claim that the headwater of the Glomma river is Mustjønna, a tiny lake about 30 km north of Aursunden.