Flowing beside us is the Isarwerkkanal. This channel tells a tale of innovation, adaptation, and Munich’s evolving relationship with its river. The Isarwerkkanal is a testament to Munich’s ingenuity. It stretches approximately 12 km through the city.
Imagine Munich in the late 19th century. The Isar River was both a resource and a challenge. To harness its power, the Isarwerke GmbH constructed two hydroelectric plants south of Munich. These were the Höllriegelskreuth plant in 1894 and the Pullach plant in 1900. To power these plants, water was diverted from the Isar into a man-made channel. This channel became the Isarwerkkanal. The canal originally flowed back into the Isar just above the Großhesseloher Bridge. Its construction went hand in hand with efforts to regulate the Isar’s flow.
The city of Munich recognized the potential of the Isarwerkkanal. Between 1906 and 1908, the city built its first municipal hydroelectric plant, Isarwerk 1. The Isarwerkkanal was extended to the Thalkirchner Bridge. Here, it returned water to the Isar. This extension also involved further regulation of the Isar.
Interestingly, the Floßkanal, previously drawing water directly from the Isar, was now fed by the Isarwerkkanal. It too rejoined the Isar near the Thalkirchner Bridge. The Isarwerkkanal’s expansion wasn’t without controversy. In 1902, concerns about preserving the natural river landscape led to the founding of the Isartalverein. While they couldn’t prevent the canal’s construction, they influenced its course and ensured the subsequent restoration of the river landscape. The city’s garden director, Jakob Heiler, designed a park-like floodplain forest. He also created the Hinterbrühler See.
Further expansion occurred between 1921 and 1923. The Isarwerkkanal was extended again to facilitate the construction of Isarwerk 2 and Isarwerk 3. It was channeled into the bed of the Großen Stadtbach. This stream had originally sourced its water from the Isar near the Thalkirchner overflows. It also fed Munich’s city streams.
In 2023, renovations began on the Großhesseloher Wehr. These renovations are expected to be completed in the autumn of 2024. The new lock gates are designed to better handle debris. A less steep passage aims to ease fish migration. The Großhesseloher Wehr has since been listed as a historical monument.
The Isarwerkkanal begins its journey in Buchenhain in the district of Munich. After passing the Höllriegelskreuth and Pullach power plants, the canal’s ownership transfers to the Stadtwerke München. South of the Großhesseloher Bridge, a weir allows water to be redirected between the canal and the Isar. Stadtwerke München operates the Isarwerk 1, Isarwerk 2, and Isarwerk 3 run-of-river power plants. From Isarwerk 2 onward, the canal follows the original course of the Großen Stadtbach. Near the Braunauer Eisenbahnbrücke south of the city center, most of the water flows back into the Isar behind Isarwerk 3. A small portion is diverted to power the Stadtbachstufe. It continues as the Westermühlbach.
In October 2018, repair work on the Isarwerkkanal led to a fish kill in the Isar. The water level dropped too quickly due to water extraction for the canal. This resulted in the death of up to one hundred thousand fish.
The Isarwerkkanal also serves recreational purposes. Rafts, a popular leisure activity, use a section of the canal. They access it via the Floßkanal, branching off above Isarwerk 1. After the raft landing, this canal flows as the Mühlbach through the Maria Einsiedel natural swimming area. About 400 meters below Isarwerk 1, the canal supplies water to the Auer Mühlbach on the eastern side of the Isar via a siphon running under the river. Below the Thalkirchner Bridge, the Maria-Einsiedel-Bach, fed by the overflow from the raft landing, flows back into the Isarwerkkanal. The canal also provides cooling water to the Heizkraftwerk Süd power plant. The Isarwerkkanal remains a vital part of Munich’s infrastructure and recreational landscape.