The Val Bregaglia (Lombard: Val Bargaja, German: das Bergell, Romansh: Val Bregaglia ) is an alpine valley of Switzerland and Italy at the base of which runs the river Mera (Lombard: Maira in Switzerland). The valley begins at the Maloja Pass (1815 m) which connects it to the Engadin (the valley of the Inn, which is part of the Danube basin) and extends westwards to Chiavenna shortly after which the Mera joins with the Liro and turns south towards Lake Como. From Chiavenna to Maloja, a distance of 32 km, the valley rises 1482 m. Most of the valley falls within the Swiss district of Maloja in the canton of the Grisons, the lower part within the Italian province of Sondrio. A 10,800 ha tract of the valley has been identified as an Important Bird Area by BirdLife International.
The Bregaglia Range is the group of mountains to the south of the valley. Curiously, it is only in this valley in the whole Europe where the sources of three important basins (which run to different seas) have their origin: the Rhine (which runs to the North Sea), the Inn (which runs to Black Sea) and the Po (running to Adriatic Sea).
The valley includes the Swiss former municipalities of Vicosoprano, Stampa, Bondo, Soglio and Castasegna (now consolidated into the municipality of Bregaglia); and the Italian municipalities of Villa di Chiavenna, Piuro, and Chiavenna.
Elektrizitätswerk der Stadt Zürich (EWZ) operates three hydroelectric power plants in the valley at Vicosoprano, Bondo and Castasegna. The hydroelectric project at Vicosoprano was formed by damming the river Albigna, forming Lake Albigna. Located approximately 1000 m above the town and set back, the site is reachable by an aerial tramway operated by EWZ.
The Swiss part of the valley is inhabited by the descendants of Italian Protestants who came to Switzerland in the mid-16th century to avoid persecution by the Inquisition, and today about 75% of the population is Protestant. The local dialect is a variety of Lombard with similarities to neighboring dialects of Romansh.