In spring, water level can be high especially if the river Marne has overflowed during winter. Typical species at this time of year then include Garganey and Northern Pintail which can easily hide into the dense vegetation. Several pairs of European Stonechat and Reed Bunting breed in the marsh and later in season it's also the case for Marsh Warbler. Even if water level is generally to high for waders on the main water body at this time of year, the adjacent flooded agricultural fields can host good numbers of them including some very rare in the Paris region such as the Temminck's Stint.
In August-October water levels drop and waders, for example Wood Sandpiper, are then visible on the main water body. In August-September a migrant Osprey is often perched on one of the electric pylons.
You can park near the fence at the entry of the path. Note that there is not a lot of space. The area is best explored by walking.