The lakes in the departmental park currently have very steep, wooded and homogeneous banks, which means that vegetation (patches of helophyte vegetation and wetland areas) cannot be planted in aquatic/terrestrial transition zones, which generally accommodate a wider variety of species. Furthermore, the few existing shoals are entirely dominated by an invasive species (water-primrose) which is threatening native wildlife in the area and partly responsible for the eutrophication of the lakes. As a result, the lakes and banks have limited appeal for nesting aquatic bids, dragonflies and fish alike.
The banks of the Seine, which stretch 2.8 km through the park, are very steep and not very conductive to the development of quality riparian wetland areas and associated flora and fauna.
Bold ecological operations are underway to restore two lakes with a view to diversifying the habitats on the banks and creating aquatic/terrestrial transition zones. The work involves creating aquatic environments, by planting reed beds and aquatic vegetation, as well as creating wetland areas, which are essential for wildlife.
Patches of helophyte vegetation (e.g. reed beds and sedge meadows) are not very common environments in the Ile-de-France region, despite the fact they could potentially house plant species of interest (e.g. grass rushes). They are also ideal habitats for the nesting of uncommon birds such as the common reed bunting, and even the little bittern, and are home to wildlife including odonates (dragonflies), lepidoptera (butterflies) and orthoptera (crickets and grasshoppers).
Aquatic vegetation surrounding species in deeper water, covering significant areas, is of value to fauna since it provides a place for nesting, migrating and wintering species to reproduce, feed and rest. These areas are also ideal locations for dragonflies, amphibians and fish to reproduce.
All of the plant species used will be indigenous to and common in the Ile-de-France region to ensure the areas in question are as natural as possible.