The Gründel ponds

To the north of the Forêt d'Exception® de Haguenau, the Gründel ponds located in the center of a forest crossroads are called "Grünes Wasser" (the green ponds).
They were dug in 1893 to extract the gravel necessary for the construction of a railway serving the Maginot Line and destroyed during the Second World War. Today cleared of trees and brush, it is used on certain portions as a hiking trail.

From March, these ponds are spawning grounds for several species of frogs and newts.
Around the ponds, there are oil wells exploited until the 1970s, some of which are still visible.