Lago Bianco, Reservoir at the Bernina Pass, Grisons, Switzerland

Lago Bianco is a reservoir in the Canton of the Grisons, situated at the Bernina Pass between the Val Poschiavo and the Engadine valley. The water appears milky white because fine sediments carried by glacial meltwater flow into the basin.

Two natural lakes, Lago Bianco and Lago della Scala, once occupied this basin; between 1910 and 1911 the Scala and Arlas gravity dams were built, creating a reservoir holding 18.6 million cubic metres for hydro-electric plants in the Val Poschiavo. The stone dams received concrete crowns raising them about 4 m in 1941–1942, and Repower renovated and resealed both walls between 1999 and 2001.

The name Lago Bianco means "White Lake" in Italian, after the milky outflow of the Cambrena glacier that fed the original natural lake. The reservoir lies on the language border: the Poschiavo side is Italian-speaking, while the Engadine side below the northern dam is Romansh and German-speaking. The Bernina railway, Europe's highest mountain crossing line, runs along the eastern shore past Ospizio Bernina station.

The lake sits right along the Bernina Pass road and is easy to reach on foot without special equipment. Visiting between June and September gives you the best chance of snow-free access, as the pass sits at high elevation.

The lake's milky colour comes from the outflow of the Cambrena Glacier, which gave the original natural lake its name. Just below the northern dam lies Lej Nair, whose water drains north to the Black Sea through the Inn and Danube, while Lago Bianco drains south to the Mediterranean via the Poschiavino, Adda and Po. The two basins sit on the continental divide.