The Saint-Ferréol Lake is located 1148 feet (350 meters) above sea level and captures the streams and rivers arriving from the Montagne Noire. The lake then feeds the Rigole de la Plaine, a small canal built on the low slope which then descends to the Lauragais plain and the Seuil de Naurouze basin, where the waters are divided between sea and ocean. This water retention base was built by Pierre-Paul Riquet, architect of the famous Canal du Midi, and is listed as a UNESCO World Heritage Site.