Was it a deliberate act of nature or a consequence of human ambition? The Arlesheimer See stands before you a testament to both. Created not by the slow hand of time but by the swift diggers of the 1960s. This artificial lake owes its existence to the construction of the A5 motorway between Karlsruhe and Basel. The massive amount of gravel needed for the project led to the excavation of this surprisingly beautiful spot.
The Arlesheimer See is more than just a body of water. It’s a hidden gem nestled in the Mooswald forest west of Freiburg. The lake itself isn’t vast. Its surface area is approximately 6 hectares. Yet it’s rich in biodiversity. Its depths reach a maximum of 18 meters. This depth combined with the surrounding marshland and reed beds creates a haven for wildlife.
Initially quite nutrient-poor because the topsoil wasn’t replaced after the excavation. It soon thrived. The arrival of many birds and a stream flowing from the Mooswald changed that. Over time the lake became a vibrant ecosystem. This is evidenced by the presence of 160 bird species. Amazingly 48 of these have been recorded breeding there. It also supports 31 different types of dragonflies and two bat species.
But the lake’s story doesn’t end there. In 1966 the Bund für Vogelschutz (BfV) a predecessor to the NABU successfully advocated for it to become a protected nature reserve. This was a bold move at the time. It meant protecting a site born from the disruption of building a highway. It’s a powerful reminder of how human intervention can sometimes unintentionally foster new life.
The designation as a nature reserve means access is restricted. It ensures the continued flourishing of this remarkable habitat. The Arlesheimer See isn’t just a pretty picture. It’s a place of scientific interest too. In 2002 a rare moss species Ulota coarctata was rediscovered here. This was its first sighting in Baden-Württemberg since 1927.
So as you stand here today reflect on the Arlesheimer See’s dual nature. It’s a lake born from industrial progress yet transformed into a vital sanctuary for wildlife. A unique place that offers a quiet reminder that nature’s resilience sometimes surprises us even in the face of human development.