Bavaria’s Inn River to be made passable for fish again

At the end of June, VERBUND Innkraftwerke will begin construction of the fish pass at the Rosenheim power plant on the Inn River. The project will restore the Inn River’s ecological passability and enhance specific features of the adjacent natural environment. All necessary permits have been obtained.

Work begins with the set up of the construction site on 22 June 2026, with construction scheduled to start on 29 June 2026. A bypass channel designed to replicate natural conditions and measuring approximately 2.2 kilometres in length will be built on the left bank of the river between the Inn Bridge on Miesbacher Straße (St2095) and the Happinger Ausee.

The Inn Cycle Path running along the reservoir dam will be diverted to the left side for the duration of the construction work. The construction site will remain closed for safety reasons, and the diversion route for pedestrian and bicycle traffic will be signposted at the location. Relevant traffic regulations apply from 22 June 2026 to 31 August 2027. VERBUND thanks road users in advance for their understanding.

The main construction work is scheduled for completion in June 2027. Final recultivation and remaining works are planned for autumn 2027.

Inn River to be made passable for fish again after 100 years

The core element of this eco-project is the construction of a bypass channel on the left bank of the Inn River. It measures approximately 2.2 kilometres in length and has been designed to replicate natural conditions. The meandering course with varying flow rates and water depths will enable all fish species and aquatic creatures to swim around the power plant while overcoming a height difference of 8.3 metres. Installation of gravel beds, sediment bars and felled trees will create an attractive habitat with new shelter areas and spawning grounds.

Once the fish pass is completed, the Inn River in Bavaria will be passable for fish and other aquatic creatures again from 2027 onwards for the first time since the power plants were constructed over 100 years ago.

Rosenheim fish pass: facts and figures

• Length: 2,215 m; width: between 8.6 m and 34 m (in the area of local island structures)
• Water depth: Between min. 0.4 m and approx. 1.2 m
• Height difference: 8.3 m
• Flow rate: Variable flow rate based on natural, dynamic outflows of a floodplain stream – basic flow rate generally 1.5 m³/s, variable additional flow up to max. 4.0 m³/s.
• In addition, possibility of temporary flushing (flushing of spawning grounds, promotion of sediment displacement of total max. 6.0 m³/s)
• Design elements: Gravel rapids, felled trees, rootstocks, sediment bars for fish and birds, shallow water zones, nesting sites and piles of stones for reptiles etc.