The Orpellières area is located at the mouth of the River Orb, in the municipalities of Valras and Sérignan. This 150 hectare site, acquired by the Conservatoire (the French Coastal Protection Agency) in 1980, comprises a beach, a 2.5 kilometre long belt of sand dunes and a vast area of salt marsh.
The contrast between the dunes themselves and the land behind them is astonishing. The belt of dunes is a warm and dry environment. The land behind the dunes is below sea level, and is therefore wet and saline. The flora and fauna of these two environments are very different.