The Gudbrandsdalslågen begins in the lake Lesjaskogsvatnet (or Lesjavatn), which lies in Lesja municipality in the far northern part of the county. Lesjavatn is the only lake in Norway which has two outlets, and they both flow into two of Norway’s more famous rivers. In the southeast at the village of Lesjaverk, the lake serves as the headwaters for the Gudbrandsdalslågen, while in the northwest at Lesjaskog village, Lesjavatn is the headwaters for the Rauma river which heads to the west.