Innerste Dam, Embankment dam in Langelsheim, Germany.

Innerste Dam is an embankment dam near Langelsheim that holds back the Innerste River and forms a drinking water reservoir serving several communities in the region. The dam sits at the edge of the Harz mountains and has the sloping earthen profile typical of this type of construction.

The dam was built during the 1960s to improve water supply and flood control in the foothills of the Harz. It is part of a group of reservoirs constructed in that era to meet the growing needs of nearby towns.

The Innerste Valley Railway once had a halt by the dam; its track through the valley was moved to the eastern slope for the reservoir's construction, and a cycle path now runs between Langelsheim and Wildemann on the old route. The reservoir is used by sailing and rowing boats and for angling and camping.

The area around the dam is easy to reach and works well for a day trip on foot or by bike. Sturdy shoes are a good idea, as some paths along the shoreline can be uneven.

Water from the Innerste reservoir can be pumped through a 4.6 km pressure pipeline to the Grane Dam to the east, where it is treated as drinking water. The pipeline is not a canal: it carries water uphill under pressure. The reservoir was fully drained from 2003 to 2005 so the asphalt sealing and bottom outlet could be repaired.