A project to raise the barrier of the Old Emosson dam has been approved by federal authorities in a move designed to boost hydroelectric output by a third.
The dam wall will be raised by 21.5 metres, an increase which is expected to increase the energy output from 600 to 900 megawatts.
The Ministry of Environment, Transport and Energy said in a statement that dam operators Nant de Drance had agreed to pay an additional SFr10.5 million ($11.7 million) in environmental compensation which enabled it to approve the project.
The Emosson dam in canton Valais pumps water into the higher-altitude Old Emosson dam, which is then returned to its lower point of origin by a central turbine.
swissinfo.ch and agencies