The 'Lac du Der-Chantecoq' is a large artificial lake (48 square km) in north-eastern France (Champagne region), built (1974) to control the water levels of the river Marne
before it flows into the river Seine. This helps preventing floods downstream during heavy rain periods.
The lake has become a resting place for some 300 bird species and a popular recreation area.
This year, in October, the water levels of the lake were very low because of the hot and dry summer months.