Aujourd'hui Aujourd'hui (≈ 2025)
Position de référence.
Key figures
Saint Gérard - Local boss
Give his name to the lake
Origin and history
The lake of Gérardmer, located in the eponymous commune, is a lake of glacial origin formed during ice retreats after the glaciation of Würm (between 80,000 and 10,000 BC). It is held by a terminal moraine blocking the valley downstream, and pours into Vologne by the Jamagne. Its elliptical shape, facing east-west, extends over 2,020 m in length and 750 m in width, with a maximum depth of 38.40 m.
The lake bears various historical names, such as the Giralmer Sea (1593) or the Gérardmer Sea (1622), linked to local pastoral traditions. In the seventeenth century he was called Grand Mer, although his present name probably came from Saint Gérard, patron saint of the local church. The surrounding toponyms, such as Ramberchamp (ubac) or the right of the lake (adret), reflect its geographical and cultural importance for Gallo-Roman and medieval communities.
Between 1977 and 1994, 12 mine clearance campaigns resulted in 120 tons of ammunition being extracted from the two world wars immersed in the lake. Despite these efforts, residual pollution persists, with high levels of lead, iron, titanium and TNT (up to 327 ng/L). Bathing and fishing remain permitted under conditions, while the lake partially feeds Gérardmer's drinking water network, although an exceptional stop occurred in 2022 due to drought.
The formation of the lake is part of that of the lake valley, including also the lakes of Returnnemer (ice circle) and Longemer (Morainic basin). These three bodies of water result from the last quaternary glaciations, which carved the Vosges massif. Their layout illustrates the different stages of glacier withdrawal, with granite locks or moraine deposits acting as natural dams.
The lake of Gérardmer, nicknamed Geroldsee in Alsatian (derived from Gérard), is surrounded by evocative toponyms such as Black Rocks (ubac) or Merelle's head (turbe pond). These names recall its central role in local practices, whether pastoral, religious (pilgrimages) or hydrological. Its status as the largest Vosges lake makes it an emblematic site of the natural and historical heritage of the Grand Est region.
