Questions and answers

During the fish migration inspection in 2005, the performance of the fish ladder, which was commissioned in 1970, was rated as inadequate. The negative assessment was primarily based on the very low number of small and weaker fish species that were found during inspections, indicating that the fish pass had a selective effect.

Consequently, in 2016, the Federal Office for the Environment (FOEN) ruled:

• The existing fish ladder has a number of deficiencies and no longer meets current standards. It must therefore be refurbished.
• In order to guarantee upstream migration in accordance with the latest standards, the fish ladder must be comprehensively renovated or rebuilt.
• The focus is on a fish pass that is as near-natural as possible (bypass watercourse), which can also be overcome by salmon.

Naturally, this possibility was examined and compared with options that foresee the construction of a new fish pass. We examined the following four options: 
1. Optimisation of the existing fish ladder
2. Construction of a new technical fish pass (vertical slot pass using concrete elements) 
3. Construction of a new short, near-natural fish pass
4. Construction of a new near-natural bypass watercourse, incorporating the creation of new habitats and spawning grounds in addition to the fish pass

Due to its narrow channel, the old fish ladder cannot be upgraded to fulfil the current standards for fish migration. This would require more space for larger basins with a lower gradient per step.
In consultation with the technical and approval authorities of the cantons of Solothurn and Berne, option 4 was determined to be the preferred solution. This was due to the significantly greater positive impact on the adjacent watercourse section of the Aare, on the terrestrial habitat and on the landscape. The pre-project was coordinated with the cantonal authorities. Subsequently, Alpiq submitted it to the Federal Office for the Environment in accordance with the prescribed procedure.

Unfortunately, none of the public car parking spaces on the forecourt of the power plant will be available, since the new near-natural basin fish pass will take up most of the forecourt. Alternative car parking spaces are available on the southern bank near the bridge over the River Aare.

No. The new watercourse is designated exclusively for the endangered fauna in the Aare. These timid animals are driven away simply when people approach the open water; the new watercourse is intended to be a natural and protected habitat.