River Ölfusá is a popular spot for birds especially during the winter time when creeks and lakes are frozen over. Due to spring water, part of the river never becomes frozen. There are several species of Gulls, mostly Iceland Gull, Whooper Swans and ducks.
River Ölfusá starts about 8 km north of Selfoss where two rivers join, a spring water river and a glacial river. One is River Hvítá which is mainly originated from the glacier Langjökull. The other is River Sog which is the biggest spring water river in Iceland. It comes from Lake Thingvallavatn (Þingvallavatn) which is usually the biggest lake in Iceland.