Erlachsee, Nature reserve with artificial lake in Karlsruhe, Germany

Erlachsee is a nature reserve built around an artificial lake in Karlsruhe, featuring shallow water areas, reed beds, and gravel islands. These varied habitats support a wide range of plants and animal species throughout the year.

The lake formed from gravel quarrying in the 1930s during Reichsautobahn construction, with additional excavation work occurring between 1969 and 1970. What began as an industrial byproduct eventually became an important natural area.

The protected area belongs to the Natura 2000 network within the Fauna-Flora-Habitat Oberwald und Alb, representing regional conservation efforts in Baden-Württemberg.

The reserve is fenced, and the lake lies in the Oberwald in Durlach, in the south of Karlsruhe. Access is on foot along the paths of the surrounding alder-ash forest; the shallow-water zones and reed beds are left to the birds, so keep to the edge and give resting and wintering ducks room.

The gravel islands in the lake are nesting sites for the little ringed plover, not the Kentish plover. In 2011 the Technisches Hilfswerk recovered a floating platform from the water; it had served as a breeding island for rare birds but had sunk through a leak, and its styrofoam buoyancy material threatened to pollute the reserve.