Mandelholz Dam, Embankment dam in Oberharz am Brocken, Germany.

The Mandelholz Dam is an embankment dam built across the Kalte Bode river in the Harz mountains, creating a large reservoir behind it. The structure regulates water flow and serves the surrounding region's water supply needs in this forested mountain area.

The Mandelholz Dam was built from 1952 to 1957 as a flood retention basin for the Kalte Bode, an earth-fill embankment with a concrete inspection gallery. South of the crest a spillway handles excess water; the dam last overfilled in the 1994 flood. Near Mandelholz on the Wormke lie the ruins of an older dam that supplied the Mandelholz Iron Works from 1612 until the 1855 flood destroyed it; it was never rebuilt.

The name Mandelholz may come from the spruce forests here, as spruce was once called Mandel in German. Behind the dam, on the Wormke, lie the ruins of the Mandelhölzer Teich, a pond that supplied the Mandelholz Iron Works from 1612 until the flood of 1855 destroyed its dam.

The dam lies between Elend and Königshütte in the Oberharz am Brocken municipality, on the Kalte Bode. A spillway sits south of the earth-fill crest, and a concrete inspection walkway runs inside the dam body. The reservoir is a flood-retention basin, so water levels vary and the structure impounds water only at high water.

Behind the dam, near Mandelholz on the Wormke, lie the remains of an older reservoir, the Mandelhölzer Teich, which supplied the Mandelholz Iron Works from 1612 until catastrophic flooding destroyed its dam in 1855; it was never rebuilt.