Hundreds of fish die as Wichelsee is lowered for construction

Hundreds of fish have died after the water level at Wichelsee, a reservoir in canton Obwalden, was lowered for construction work, SRF reports. Fisheries officials rescued about 200 fish, but could not save the rest.

The lake was lowered by just over a metre to allow construction of a fish passage at a hydroelectric power plant. The passage is intended to help lake trout and eels leave Wichelsee for Lake Alpnach and Lake Lucerne. They currently have to pass through the plant’s turbine, which kills many of them.

Christoph Hug, a spokesperson for Centralschweizerische Kraftwerke (CKW), which operates the plant on behalf of Kraftwerk Sarneraa AG, said some fish had reached deeper parts of the lake, but not all had survived. He said it was impossible to catch all the fish before lowering the water, and that fish hiding in the reed belt could not be reached without causing damage.

Obwalden fisheries officer Armin von Deschwanden also said the operation posed challenges. He tried to rescue fish but had to stop after sinking up to his thighs in the muddy, exposed lakebed.

Wichelsee is now divided into three separate basins where the remaining fish have taken refuge. The water level is due to fall by another 1.5 metres at the end of the month. CKW plans to lower it gradually and monitor the basins, and will consider another rescue effort if their levels continue to drop.

CKW expects to finish the fish-passage work in January and refill the lake. It aims to restore the normal water level by the start of the fish breeding season in late February.