Hydropower Reservoir in the St. Gallen Calfeisen valley is emptied for renovation

The three-kilometre-long Gigerwald reservoir in the Calfeisental in the canton of St. Gallen will be completely drained by the end of September for a partial renovation of the dam. The work is necessary due to the progressive silting up of the reservoir.

The energy company Axpo and Kraftwerke Sarganserland announced on Wednesday that the silted-up lake bed has already reached the height of the bottom outlet. The inlet of the bottom outlet will therefore be moved 20 meters higher. The costs amount to 25 million Swiss francs.

"In order to be able to operate the plant safely for the coming decades, the necessary structural measures can no longer be postponed," Axpo wrote.

In order to protect the fish stocks in the Tamina below the reservoir from the impact of the construction work, the mountain river was fished out over a length of almost four kilometers. This ensures that as few fish as possible are harmed by the residual lowering of the lake.

The work on the dam is expected to last until April 2025, with reopening scheduled for early summer 2025.