Lake Leirvogsvatn is in Mosfellshreppur by the road to Þingvellir National Park. It is 1.2 km², a maximum depth of 16m and is at 211m above sea level. Bugða runs into the lake from the north and Leirvogsá runs out from it to the sea. Leirvogsa is a good salmon river. The lake has both brown trout and char, good numbers of fish, but not large fish. The Þingvalla-road (no. 36) runs by the lake. The lake is owned by the churchyard Mosfell and the land Stardals and the residents use the fishing rights mostly themselves, but the priest at Mosfell gives permission to fish in his land free of charge.