Ostensjovannet lake

Ostensjovannet is a lake in Oslo, capital of Norway. It is well-known for the wide variety of birds and other wildlife that can be found there. It is surrounded by the Ostensjo borough. It is currently a wildlife preserve, though urban development posed a serious threat to the lake and its environs during the 1980s and early 1990s.

Ostensjovannet is well known for its birdlife, and over 200 different species of birds have been sighted at or near the lake, quite a significant number by Norwegian standards.

Other wildlife is regularly sighted at the lake, but the variety of species is not much different from surrounding places, such as Ostmarka.

Fishing during the summer is forbidden, while ice-fishing is allowed.

Situated inside the Oslo city limits, surrounded on all sides by built-up areas, has put a considerable strain on the lake, both in terms of pollution (especially caused by leaks from less-than-perfectly maintained sewage systems) and plans for using the fields and forested areas surrounding the lake for various purposes, including housing, a cemetery and even a small golf course.

The lake itself has been a wildlife preserve since 1992, while Abildso Farm was preserved by the Norwegian Riksantikvar in 1997. June 11, 2002, the Oslo city council passed plans for the "Ostensjovannet Environmental Park", which in effect preserves the various habitats and "green areas" surrounding the lake.

The sewage systems affecting the lake have been better maintained in recent years, and the environmental state of the lake is currently much better than it was a decade or two ago. (Ostensjovannet lake)