The Heilenbecketalsperre was built in the years 1894 to 1896 on the territory of today's cities Ennepetal - near the district Rüggeberg - and Breckerfeld in Ennepe-Ruhr-Kreis (North Rhine-Westphalia) and is the oldest dam in South Westphalia. The dam is operated by the Heilenbecke water association.
It is dammed by the Heilenbecke, which flows into the Ennepe, 7.5 km below the dam near Ennepetal-Milspe. With a maximum capacity of 450,000 m³, the water surface of the reservoir is 8.5 ha.
Originally, the Heilenbecketalsperre was a water reservoir for the hammer mill and Schleifkotten, which were located along the Heilenbecke. Today, however, it serves primarily the drinking water supply; besides the increase of the Ruhr at low tide.
The dam wall is a gravity dam made of quarry stone masonry with a height of 19.5 m, a crown width of 4.1 m and a crown length of 205 m (before refurbishment 2.8 m and 162 m, respectively). It was built to the designs of Otto Intze 1896 and rehabilitated from 1988 to 1990, where it was strengthened and provided with a control passage. In addition, she received a concrete wall, a drainage wall, a new mural crown and new facilities.
The dam is a popular area for hikers and joggers with a circular trail of about 2.4 km. The restaurant, which was located directly at the parking lot, was destroyed in the summer of 2006 by a fire to the ground and not rebuilt.
The dam was listed as a technical monument of local importance, which is to preserve and use for scientific and architectural reasons, listed.