It is located at Sainte-Colombe-sur-l'Hers on the border between the Ariège and Aude départements of southwestern France.

The flooded hillsides are still evident when the water level drops, revealing tree stumps and the thick sticky clay (marl) so typical of the Ariège.

On quiet hot summer days the water takes on a beautiful turquoise colour which is very photogenic.

Other lakes for swimming near Montbel include Lac de la Cavayère and a smaller one at Pradelles-Cabardès.

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