In Graubünden, Lake Bianco at its lowest level since the start of the millennium

Lake Bianco, at the Bernina Pass, is currently only about half full. Over the average of recent years, the reservoir was typically around 70% full at this time of year. "In questo millennio il livello a metà agosto non è mai stato così basso" (in English: "In this millennium, the level in mid-August has never been this low"), Stefan Bisculm of Repower's press office, the group that operates the hydroelectric plant, told RSI. Already last July, the lake had reached its lowest level in twenty years.

The prolonged heat and drought have reduced inflows into the reservoir. Repower has therefore adopted a more cautious management of water resources: a lower level means less water available for electricity production, and consequently a reduced production potential.

The goal: a full reservoir by winter

The company now aims to use the available reserves so that Lake Bianco is completely refilled by winter. However, the actual water level will largely depend on precipitation and inflows in the coming months. On the electricity production front, Repower says it is not currently concerned: experience from previous years shows that a low water level in summer does not necessarily mean the reservoir will also be below average at the start of winter.

The case of Lake Bianco reflects a broader trend. In Graubünden, the fill level of storage reservoirs stands at 54%, according to the latest data from the Federal Office of Energy. In Ticino, the figure drops to 46%, compared with a Swiss average of 67%. It is precisely the Alpine cantons, which host a large share of the country's hydroelectric production, that find themselves below the national average.

Water availability in Alpine reservoirs supports jobs in the valleys and a significant share of Switzerland's electricity supply, a public service that households and businesses rely on throughout the year. If dry summers like this one become more frequent, managing water reserves will increasingly require balancing energy production with the protection of a resource that ultimately remains limited.