Germany's oldest dam

With the sharp rise in silver production in the first two decades of the 18th century, it became necessary to dam up the Oder at the inlet weir of the Rehberger Graben in order to better supply the mines with slurry water. The Oder pond was built for this purpose between 1715 and 1721.

With a capacity of 1.7 million cubic metres, it is the oldest dam in Germany. The 166 metre long, 19 metre high dam has stood the test of time to this day. The contents of the pond were sufficient to supply the water wheels of the Sankt Andreasberg mines for three months during dry spells.

Unique construction of the Harz pond dam

The most famous of the Harz pond dams differs in its construction from the other rather standardised Upper Harz pond structures. This special masterpiece makes the Oderteich the most important sight of the Oberharz water management. Instead of a supporting structure of earth and stones compacted with turf, the pond dam of the Oderteich consists of large granite stones and granite sand. In accordance with the Harz construction method, a thick, mortarless cyclopean masonry was built on the air and water sides from hewn granite blocks. A core seal of tamped granite sand was placed in between. This has a high proportion of kaolinite, a clay mineral that is formed during the weathering of feldspar and binds sand grains. When tamped down mechanically in particular, this creates a water-impermeable sealing compound.