The Gründel ponds in the forest of Haguenau

To the north of the forest, the Gruendel ponds located in the centre of a forest crossroads are called "Grunes Wasser" (green ponds). They were dug in 1893 to extract the gravel needed to build a railway line destroyed during the Second World War. There are still many remains of the line. It is now cleared of trees and brush and used on some portions as a hiking trail. From March onwards, these ponds are spawning grounds for several species of frogs and newts. Around the Gruendel ponds, there are oil wells that were exploited until the 1970s. Many traces of this activity are still visible, including some wells.