Due to erosion following major flooding, the access to the fish ladder at the Reichenau power plant had to be rebuilt. An impact assessment conducted over a period of around two years has shown that the number of fish using the ladder has risen sharply again.
In 2019 and 2020, repeated and severe flooding had made it much more difficult for fish to access the fish ladder at the Reichenau power plant. Among others, this affected the highly endangered lake trout, which was no longer able to reach its spawning grounds in the anterior and posterior Rhine. As a result, the canton of Graubünden obliged Kraftwerke Reichenau AG to restore the fish ladder at the counter-weir of the Reichenau dam.
The renovation of the fish ladder is a success story. Thanks to close coordination between the Graubünden Cantonal Office for Hunting and Fishing (AJF), the Federal Office for the Environment (FOEN), Kraftwerke Reichenau and Axpo, it was possible to carry out the work in an accelerated procedure. Within just one year, a fish-friendly block ramp was planned, approved and completed in summer 2022 - just in time for the main migration period of the lake trout. The block ramp consists of large natural stones arranged in such a way that they can withstand floods and, at low tide, offer fish a passable route in specially designed channels. This allows the fish to reach the fish ladder, which has been in place since 2000, without difficulty.
Seven times more fish
The impact assessment, which was completed in 2024 and took around two years, showed that the refurbished fish ladder works perfectly. The block ramp is stable and meets the requirements for fish passability. The number of ascending lake trout, which were recorded by means of annual trap catches, has increased sevenfold since 2020 - from 40 to 286 fish. It is particularly encouraging to see that smaller fish also use the ramp, a clear sign of its functionality. The successful renovation is an important contribution to the preservation of the lake trout in the Alpine Rhine.
