Depleted Swiss reservoirs need wet autumn

Swiss reservoirs, which are relatively low, must hope for a wet autumn Keystone-SDA

Swiss reservoirs are significantly less full than usual for this time of year. There are fears of an energy shortfall in the event of a dry autumn and winter.

If reservoirs remain low, more electricity will have to be imported from abroad.

+ Should Switzerland prepare for a severe drought this summer?

“Reservoir levels are very low in Switzerland, but also across the Alpine region and in the Nordic countries,” Axpo analyst Andy Sommer told the AWP news agency.

Statistically speaking, 2026 is set to be a warm year, with year-on-year fluctuations centred around the warming trend resulting from climate change. Within this trend, cooler and wetter years are also to be expected, said Sommer.

According to the latest figures from the Swiss Federal Office of Energy, Switzerland’s reservoirs are currently 42.7% full. This means water levels are 15.1% lower than the average for the same time of year over the past 20 years.

+ Inside Switzerland’s giant water battery

The more water stored in Swiss reservoirs during the summer, the more electricity can be generated in winter, when demand is higher. If all reservoirs in Switzerland were completely full, a total of around 8,900 gigawatt-hours of electricity could be generated using dams.

There are over 50 reservoirs in Switzerland. The reservoirs in the canton of Valais account for 45% of the total storage capacity. Reservoirs in Graubünden account for 22% and 14% in Ticino.

Alpiq has a stake in the Grande Dixence, Emosson and Gougra reservoirs in Valais, all three of which are heavily dependent on inflows from glaciers. “In May, some of our reservoirs reached their lowest levels in the last ten years,” the company said.

Since then, the Valais reservoirs have filled up well again. And although current water levels remain below average, they have not reached a new record low.

“We expect the reservoirs to be well filled by autumn and ready for winter production,” said Alpiq, referring to the three plants in Valais.

In the cantons of Ticino and Graubünden, however, the situation is more precarious. Last winter, rainfall was low, and snow reserves in these regions reached a historic low.

+ How we produce English news
Translated from German, reviewed by an English Department journalist.