Ismaninger Speichersee – the paradise of ornithologists – district of Munich

Of course, the people of Aschheim are a bit nauseous. That the reservoir, which is actually located on the site of the municipality in the eastern district of Munich and the neighboring municipalities of Kirchheim, Pliening and Finsing and hardly touches the Ismaninger area, bears the name of the neighboring municipality. But it has burned in, the body of water north-east of Munich is now known as the “Ismaninger Speichersee” by day trippers and visitors from near and far. It didn’t help that the then mayor of Aschheim, Helmut Engelmann, had signs put up a few years ago with the name “Aschheimer Speichersee – Ramsargebiet”; the name “Ismaninger Speichersee” was so established that it remained in use.

Why actually? The Aschheim local historian Peter Stilling also searched for an answer to this question for a long time. For years he has been collecting old photos from the area, recording memories and anecdotes. Several films on the history of the community have already been made from his collection. He also filmed the construction of the reservoir. The seven kilometer long lake with a surface area of ​​580 hectares was created in 1929 as a reservoir on the upper reaches of the Middle Isar Canal. The canal branches off at Oberföhring and leads the water back to the riverbed of the Isar via five power station stages near Landshut. Energy generation in the canal can be regulated via the reservoir. In addition, the reservoir with the sewage fish ponds directly to the south, which were managed by Teichgut Birkenhof, was used for almost four decades to treat Munich sewage in a biological way: Carps were kept in the ponds, which found food in the mechanically pre-cleaned water from the sewage treatment plants and it so keep cleaning. This method was used until the late 1990s.

But the reservoir does not only serve the people. Birds also soon discovered the new body of water and settled on the spacious area surrounded by protective greenery to breed, rest and moult. This did not go unnoticed by bird lovers. Above all, the high school teacher and enthusiastic ornithologist Walter Wüst, who worked for a long time at the Munich Wilhelmsgymnasium, established the reputation of the water as a bird paradise. Wüst, who died in 1993, opened up the fascination for birds and their world to many young people. From 1953 to 1972 he headed the Ornithological Society in Bavaria. “Walter Wüst is something like the doyen of Ismaninger ornithology,” says his successor Manfred Siering, who has headed the ornithological society since 1994. And it was Wüst who coined the name of the reservoir, both in the vernacular and in specialist literature.

Open detailed view

The reason for the geographically incorrect naming lies in a practical circumstance. Wüst traveled publicly to his observations. And that was much easier to do via the municipality of Ismaning, north of the reservoir lake, which had had a rail connection since 1909, which had once been created for transporting the herbs grown there to factories in Munich. “Most ornithologists came by bike on the train,” remembers Siering. Since he reached the lake from Ismaning, it was obvious that Wüst also called it “Ismaninger Speichersee”. His followers adopted this name and introduced it into the ornithological specialist literature, from which it is impossible to imagine life without it today.

“It was like I was in another world.”

The Ismaninger reservoir has been classified as a wetland of international importance since 1976, and today it is part of the European biotope network Natura 2000. The State Association for Bird Protection (LBV) counts the lake as one of the most important moulting centers for waterfowl in Central Europe, in addition to its function as a resting and wintering site. It appears in hundreds of professional papers. Siering got to know the reservoir years ago through Wüst and is still fascinated by the area today. “When Walter Wüst opened the small door to the reservoir area and closed it again behind our excursion group, I felt like I was in another world. Wüst showed us his world,” Siering recalls. “I still remember how a Wohrweihe flew past with an elegant flapping of its wings and looked down at us. At the reservoir we easily discovered, heard or saw about 80 species.”

Open detailed view

Siering continues Wüst’s legacy. When carp farming in the ponds was abandoned in 2000, he lobbied the state government for the ponds to be preserved as a protected area. Since then, the Bavarian Nature Conservation Fund has stepped in. At the beginning of December, Siering led an excursion of the BLV university groups through the site. The diversity of bird life in this small paradise fascinates the 76-year-old to this day. Almost all duck species common in Germany settle at the reservoir, from the Garganey to the Gadwall to the Red-crested Pochard, which moults in summer. Various warblers can be spotted, as can warblers and orioles. The black kite breeds on the trees in the alluvial forest before escaping the cold to Africa. Even now in winter there is life at the lake, the loon, for example, is on the move; most recently, Siering sighted tundra bean geese from Siberia, to which the Swede Selma Lagerlöf created a literary monument in her Nils Holgersson novel. “We have enormous numbers of individuals here,” enthuses Siering. “And there is no other area in southern Germany that has such long time series – since 1927.”

Aschheim’s local historian Peter Stilling has revised his film on the construction of the Middle Isar Canal and added more finds. The new version is expected to be seen in spring 2023.