Once a muddy marsh, the area surrounding the Étang de la Dame lake at the lower level and north of Georges Pianta medical centre is now one of Thonon-les-Bains’ largest public parks.

There are two schools of thought about where the name comes from. One faction believes that the lake’s name dates back to Roman times when a statue of a water goddess was found. Another says that the lady in question was Madame De Lort, a local benefactor who donated her springs to Thonon to provide the town with drinking water in 1859.

The lake is a water table outcrop in a natural depression. Due to the muddiness of the lake, the water services stopped the water from the lake being distributed as drinking water in 1953.
In 1995, the Hôpitaux du Léman gave the park to the town of Thonon in a land exchange.

This 25,000m² park was designed by Thonon’s Parks and Gardens Department (Espaces Verts) in 1996. This meant clearing the park, selecting and enforcing existing plantlife, landscaped earthworks, designing a networks of pathways, installing wooden bridges and steps, planting trees and bushes that thrive in a humid climate, fitting benches and bins to create one of the town’s largest landscaped parks from a marshland which once had a polluted, boggy pond.

Nowadays when you walk through the park you may pass by patients out of their hospital room to get some fresh air, families having a walk and fishermen with their permits here to fish in the lake.