river, rising in the Cévennes mountains, near Mont Lozère, in Lozère département, southern France, flowing about 300 mi (480 km) generally west to join the Garonne River near Aiguillon, draining a basin of about 4,400 sq mi (11,400 sq km). In its sinuous course, the Lot crosses the Causses (limestone plateaus) in a deep gorge. It flows west from Mende, past Entraygues-sur-Truyère, where it receives its most important tributary, the Truyère, which in its upper course is dammed for generating hydroelectric power.

The Lot River continues through the Aveyron coalfield near Decazeville and past Cahors (the old capital of Quercy) and the medieval town of Villeneuve-sur-Lot before entering the Garonne. It is canalized and navigable upstream from the Garonne for 160 mi (260 km) but is little used.