Lake of Gruyère

Lake of Gruyère (French: Lac de la Gruyère; German: Lac de la Gruyère or Greyerzersee) is an artificial lake in the La Gruyère region of the Canton of Fribourg, Switzerland.

Rossens dam

Lake of Gruyère Lac de la Gruyère
Lake of Gruyère Lac de la Gruyère
Map
Coordinates	46°39′N 7°06′E
Type	reservoir
Primary inflows	Saane/Sarine, Sionge, Jogne
Primary outflows	Saane/Sarine
Catchment area	954 km2 (368 sq mi)
Basin countries	Switzerland
Max. length	13.5 km (8.4 mi)
Surface area	9.60 km2 (3.71 sq mi)
Max. depth	75 m (246 ft)
Water volume	220×10^6 m3 (180,000 acre⋅ft)
Surface elevation	677 m (2,221 ft) (max)
Islands	Ile d'Ogoz, four other islets
Settlements	see article

The reservoir was formed between the cities of Bulle and Fribourg, by building the Rossens Dam on the Sarine river in 1948. The arch dam has a height of 83 m and a crest length of 320 m. The reservoir filled in about four months after completion. The dam is operated by the Groupe E SA.

The remains of the castle of Pont (or Pont-en-Ogoz) and a chapel are located on the Ile d'Ogoz, one of the five islets in the lake.

The "Viaduc du Lac de Gruyère" of the A12 motorway was built in the 1970s. The bridge has a total length of 2043 m and crosses three valleys, including two arms of the lake.