New fish ladder for the River Aare launched in Thun
Energie Thun AG has started the construction of a new fish ladder at the Aare works with the ground-breaking ceremony. The new construction is due to be commissioned by March 2028. The majority of the facility is being realised by Frutiger AG.
Energie Thun AG officially began the construction of a new fish ladder in the Selve Thun Aarewerke with a ground-breaking ceremony on 1 September. The preliminary construction work had already started in January 2025. The new fish ladder with two entrances will enable improved fish migration. Commissioning is scheduled for March 2028. The project is being financed via the grid surcharge fund, which is fed via a surcharge on the electricity price.
The construction was necessary because the damming of the Aare at the Aaare works by a flap weir is hindering undisturbed fish migration. There is currently only one entrance in the tailwater at the little-used power plant 94.
Energie Thun submitted the project application back in 2013 after the need to restore fish passability was recognised as part of the recertification of the Aare power plants with the naturemade star environmental label. The Office for Water and Waste (AWA) approved the early restoration in 2014. This was followed by several years of preliminary examination and development of the construction project. The overall construction decision was made in 2022 and tenders were invited in 2024.
The contract was awarded to IG ThunFisch, a consortium of IUB Engineering AG, Kissling Zbinden AG andthe fish ecology department of Kraftwerke Oberhasli AG. The largest part of the fish ladder is being built by Frutiger AG, which specialises in special civil engineering and hydraulic engineering.