Some fish such as salmon need access to freshwater but obstacles such as dams and hydropower plants can act as barriers and prevent them migrating and spawning.
However, rivers in Switzerland, which are all regulated, have benefitted from some innovative solutions to reduce the impact of hydropower plants and dams on fish. To solve this challenge, bypass channels or fishways have been built at almost at every dam and weir.
Left photo: Rheinfelden fish pass facility. Middle photo: a rock cascade pass. Right photo: a vertical slot pass (photos by Sini Olin, SYKE).