After the construction of a water catchment for artificial snow, the ski resort of Val-Thorens and the SETAM (Société des Téléphériques de Tarentaise Maurienne; Tarentaise and Maurienne' cable-car society) must propose remedial and compensatories measures for the environmental impact on the protected plant Silene sudetica (red list of protected species). The Vanoise National Park has initiated a project, financed by the SETAM, to improve the management of the wetlands. Indeed, many wetlands have been destroyed or deeply disturbed since the creation of the ski area. The main part of the watershed is located between 1900m and 2400m and is formed by a network of wet peat meadows, mesotrophic ponds, streams and meadow brooks. The study has begun in 2008 and is leaded by the Cemagref of Grenoble. We present the two phases of the project: the knowledge of the reference ecosystem and the planning of the restoration. For the first phase of the project, we used aerial photography, soil and water measurements and floristic dataset to know how was the structure of the wetlands and of the watershed before the construction of the ski area. This method allows to specify the impacts that the different types of construction (ski slopes, cable-car building, roads) have had on the wetlands. In the second phase we show how these data helped us to design the restoration project of one of the wetalnds of Val Thorens.