Lac de Montsalvens, Reservoir in the Canton of Fribourg, Switzerland

Lac de Montsalvens is a reservoir in the Canton of Fribourg, Switzerland, created by a dam built on the Jogne river. The water is fed by mountain streams from above, and the dark, clear lake is surrounded by forests, rocky slopes, and rolling pastures in a sheltered valley.

The Grand Council approved the dam on 17–18 May 1918, and work ran from 1920 to 1921, when the lake filled. Planned by Jean Landry and H.E. Gruner and calculated by Alfred Stucky, the 52 m high, 110 m long wall was Europe's first arch dam curved both horizontally and vertically. Budgeted at 11 million francs, it cost over 21 million, straining the finances of the Entreprises Électriques Fribourgeoises.

The dam and lake lie on the route to the Jaun Pass between Broc and Charmey, and the reservoir covers parts of the Javro and Motélon side valleys below Charmey. The dam itself stands half in Broc and half in Châtel-sur-Montsalvens, and its water feeds the Broc power plant through penstocks, supplying more than 13,000 households.

The walk around the lake is easy and takes about three hours to cover roughly nine kilometers, though the ground can become slippery after rain. Sturdy footwear is recommended, and the route follows the shoreline through forests and open hills with good bus access from the villages of Châtel-sur-Montsalvens and Charmey.

The dam's planners were Jean Landry of Lausanne and engineer Heinrich Eduard Gruner, while Alfred Stucky refined the calculation methods for arch dams during its construction. Budgeted at 11 million francs, it ended up costing over 21 million, a 91% overrun that briefly strained the finances of the Fribourg electricity works.