An important inland locality for migrating and wintering waterbirds and waders in southern Norway. Several species of waterbirds feed, and numerous nationally rare species breed at the site. Human activities include nature conservation, recreation, fishing and boating. There is a bird observatory at the site. The largest inland delta in Norway includes low islands and land giving way to Lake yeren.
Vegetation includes deciduous forest, scrub, grassland, and cultivated land.
The lake is one of the most important areas in southern Norway for resting migratory waterbirds. Up to 1,000 swans occur in late autumn, while large numbers of various ducks occur during both spring and autumn migrations. The nationally rare frog Rana arvalis is also found at the site. Human activities include fishing, recreation, and agriculture. Ramsar site no.