Lac d'Artouste, lake in France

Lac d'Artouste is a natural glacial lake in the Ossau Valley, raised by a slightly curved concrete gravity dam 27 m high, at 1,997 m altitude. The Pyrénées National Park borders three of its four sides. Its deep blue water fills an elongated basin edged by pale tan and gray stone, with green slopes and rocky ridges rising directly around it.

The lake took its present shape through glacial action thousands of years ago that carved the valley and basin. A dam was constructed in the 1920s to expand the natural water body and store water for electricity generation, fundamentally changing the site's purpose.

The lake lies in the Ossau Valley, a Béarnais-speaking area of the Pyrénées-Atlantiques, and its name is written in French; the sources give no Basque etymology for it. Since 1929 the water has fed the Artouste hydroelectric plant, and the small train built for the dam works now carries tourists from Fabrèges. The lake is bordered on three of its four sides by the Pyrénées National Park.

The lake cannot be reached by car; visitors must park at Fabrèges station and take the rack railway to reach the upper area. From the mountain station, a gentle 10-minute walk on a maintained trail leads directly to the water's edge.

The railway to the dam site was built between 1924 and 1929, starting from the Pic de la Sagette, which workers reached by cable car, because the Soussouéou valley has no road. The line now runs as a tourist train from the Fabrèges mountain resort on the right bank of the Lac de Fabrèges.