Lampy is a part of the Canal du Midi water supply system just as Saint-Ferréol lake. This reservoir was created to compensate the volume of water needed for the Canal de Jonction, that was opened in 1787 in the direction of Narbonne. The lake is in the Montagne Noire region, in the town of Saissac (Aude). It is located on the Lampy river, upstream from an older reservoir alongside the mountain channel, known as Lampy-Vieux (now dried up).
A former water reservoir, today known as Lampy-Vieux is part of the modifications made by Vauban to the initial network. This reservoir was used to regulate the flow of the Rigole de la Montagne Noire channel, and was also designed as a settling basin. This original reservoir was built at an altitude of 630 m and covered a surface area of around 6 hectares.
Unfortunately, the reservoir turned into marshland over time. In the 1920s, it was decided to dry it up to stop the spread of mosquitoes in this area where the tourism industry was developing.
This plot of land has now completely dried up and has been replaced with a forest. The only remainder of Lampy-Vieux today is a part of the dam. To make sure the water from the Rigole de la Montagne channel flows over the former dam, a concrete aqueduct was built in the 1940s.
This lake could satisfy the increased demand due to the opening of the new Canal de Jonction, linking the Canal du Midi to the Canal de la Robine de Narbonne. This new reservoir was built upstream from the first one, at an altitude of 643 metres, and was completed in 1782. The water supply comes from Lampy and Lampiot streams, which flow into the Rigole de la Montagne channel at the location of the former Lampy-Vieux reservoir.
This lake is over 130 m in length and exceeds 16 m at its highest. It has a capacity to store 2.6 million m3 of water and covers a surface area of 23 ha.
Overlooking the main beach on the shores of Lampy Neuf is the Leignes dyke. It is 75 m long and encloses the small valley of the same name, containing the water inside the reservoir when it is at full capacity.