Lake Der-Chantecoq (French: Lac du Der-Chantecoq, pronounced [lak dy dɛʁ ʃɑ̃tkɔk]) is situated close to the commune of Saint-Dizier in the departments of Marne and Haute-Marne. It is the largest artificial lake in France, covering 48 km2 with 350 million m³ of water. The lake is named after the Der plain, in which it is located, and the submerged village Chantecoq.
The lake is fed by a 12 km long canal that branches off the river Marne in Saint-Dizier. The outflow of the lake is a canal that joins the Marne in Arrigny, 20 km downstream of Saint-Dizier.
