The Salzachseen are artificial lakes that were created in the course of the motorway construction in 1938. They are an important recreational area for the locals and among the closest "borderline-natural" swimming opportunities from the city of Salzburg. They can be found on the left shore of the Salzach River in the north-west of Salzburg, not far from the Saalachspitz. They belong to the district of Liefering.
Their creation was unintentional and linked to the use of rubble that was mined from this area as a base for the motorway construction. Mining was continued after 1938 to build sound protection barriers along the motorway. Specifically, these were built over the course of several years and gradually developed. This section of the motorway was opened to the general traffic only in 1955. Between 1945 and 1955, it served as a race course and for other sport events.
The Salzachseen are a cluster of water bodies, ranging form tiny ponds to proper lakes. The best-known are four of the larger lakes: The Vogelsee is the most remote and "natural" one; it became a popular breeding ground for local birds. The "Großer Salzachsee" and the "Lieferinger Badesee" are probably the best-known, the latter one is a popular swimming area.
The "Karlsbader Weiher" was named after a town in Bohemia and commemorates the thousands of ethnic Germans that were expelled from today′s Czech Republic after World War II. Many of them moved to Salzburg and Liefering was among the most popular areas for them to settle. In addition, there are several smaller ponds and lakes that are often private property. The wetlands and lakes of the Salzachseen have become a valuable ecosystem, despite their unnatural origin. They compensated in part for the loss of habitats caused by the training of rivers and creeks especially in the 1950ies and 1960ies.
Salzachseen Lakes on Wikipedia in German