It was laid out in the Ecker catchment area at the foot of the Brocken massif, characterised by extended upland bogs and heavy precipitation of up to 1,700 mm (67 in) a year.

The reservoir uses a section of the river valley which, below a prominent trough end, was dug out in the shape of a basin by an ice age glacier.

Construction started in 1939, mainly to meet the increasing demand for drinking water in the Brunswick greater area and around the recently opened Wolfsburg Volkswagen Plant.

Works continued throughout World War II, when the Nazi authorities also deployed foreign workers (Fremdarbeiter) and POWs to complete the facilities.

The Border Troops of the German Democratic Republic had walls and barbed wire mounted on the dam crest and only about two-thirds of the facilities were accessible from the west.