The Mandelholz Dam (German: Mandelholztalsperre) holds back the Kalte Bode Flood Control Basin (Hochwasserschutzbecken Kalte Bode) which is a flood protection reservoir located between the villages of Elend and Königshütte near Wernigerode in the Harz mountains of Germany.

In order to protect the crest from overspill, a spillway has been constructed south of it to handle excess water.

The last time the dam was overspilled due to high water was in 1994.

Catastrophic flooding in 1855 destroyed the dam and it was not rebuilt.

The name Mandelholz as a place name may be derived from the spruce forests in the area, because spruce trees used to be called Mandel in German.