As the name implies, it used to be a marsh until construction works for the student apartments at Lappkärrsberget punctured a subsoil spring in the 1960s.

Today, the lake empties into the strait Lilla Värtan through a culvert and forms part of a proposed nature reserve in Norra Djurgården.

Local land usage produces small amounts of nutrients and no conduits guides surface water to the lake.

Notwithstanding various levels of chlorophyll, water transparency exceeds the depth of the lake and pH is reported as constant.

[3] Both the lake and the surrounding national park is easily accessible by metro, bus, bicycle, or by foot.