A major freshwater river that drains Lake Thingvallavatn. Land-uses also include angling (salmon fishing), hydroelectric generation and holiday-homes. The area belongs to three communities: Grafningshreppur, ölfushreppur and Grímsneshreppur.
One of the few wintering sites for Bucephala islandica in Iceland away from Mývatn-Laxá (site 044). Also overwintering, in notable numbers, are Bucephala clangula (one of the few wintering sites in Iceland) and Mergus serrator.
BirdLife International (2019) Important Bird Areas factsheet: Sog. Downloaded from http://www.birdlife.org on 16/12/2019.