The storage lakes are an important support for the electricity supply in winter. The more water is stored in the lakes, the more electricity can be produced with it. There are "simple" storage power plants and pumped storage power plants. In the latter, water can be pumped back into the upper storage basins, e.g. when electricity prices are low. In the case of the simple storage power plants, it is mainly the natural inflows of water that increase the storage level. The storage lakes are thus a kind of battery for the cold winter months, when the demand for electricity is greater than in summer. The degree to which the reservoirs are filled is therefore an important indicator. However, the electricity from (pumped) storage power plants is not only needed in Switzerland, but is also integrated as a battery in the European interconnected system and is used on a market basis. The electricity can therefore also be exported.

The graph shows the filling level of the storage lakes in the regions of Valais, Grisons, Ticino and the rest of Switzerland. It shows the current level, the lowest level, the highest level and the average level per calendar week in percent for the last 10 years.

Also shown is the hydropower reserve held in reserve for the winter. It serves as insurance in case of critical supply shortages in winter.

The trend shows the development of the filling level compared to the previous week.

Disclaimer Data

The information on the filling levels comes from the Weekly Report "Filling Levels of Storage Lakes". The operators collect the filling levels during the night from Sunday to Monday (lake level at midnight) and transmit this information to the SFOE by Wednesday of the following week. The SFOE checks the data, aggregates them into filling levels for the regions and publishes them on Thursday.