Swiss water reservoirs are unusually depleted for this time of year, reaching their lowest seasonal level in at least 20 years.
According to the latest weekly data from the Federal Office of Energy (FOE), they are 46% full—16.4 percentage points below the average for the same point in the year over the past two decades.
The unusually low levels reflect a combination of poor winter snowfall and an exceptionally dry spring. Federal data show that spring 2026 was among the driest since nationwide records began in 1864.
Despite the shortfall, the federal government sees no immediate threat to Switzerland’s electricity supply. Reservoir hydropower typically provides about one-fifth of winter electricity demand, and Andreas Jöckel of the Federal Electricity Commission (ElCom) says there is no reason to expect shortages in either the short or the long term. He cautions, however, that the outlook remains uncertain and will depend on rainfall over the coming months.
Alpiq, one of Switzerland’s largest hydropower operators, also expects reservoir levels to recover. The company, which has interests in the Grand Dixence, Emosson and Gougra reservoirs in Valais, said last week that recent heat had substantially increased inflows as glaciers melted. Those reservoirs remain heavily dependent on glacial runoff. That source of water will not last indefinitely. As glaciers continue to retreat, summer meltwater will diminish.
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