The Hassel Vorsperre is located northwest of Hasselfelde. Its gravity dam, which dams the small river Hassel, was built between 1956 and 1959. The concrete bulwark is 21.5 meters high, 141 meters long and two meters wide at the top of the wall. The approximately 1,700 meter long and up to 250 meter wide reservoir holds approximately 1.47 million cubic meters of water at maximum storage. It covers an area of approximately 25 hectares. In addition to the Hassel, which gives it its name, various other small and unnamed streams flow into the reservoir.
The Hasselvorsperre reservoir, which is normally full to the brim, is part of the Rappbode dam system. The dam is mainly used to pre-clean drinking water. Suspended solids and other coarse contaminants settle on the bottom of the artificial lake. The water then flows - freed from these unwanted particles - via the overflow on the dam wall towards the main dam.
After more than half a century of service, the reservoir was extensively renovated in 2014. As part of this construction work, which lasted several months, the wall crown with the railing as well as the overflows and the valve house were renewed.
Over time, the man-made body of water has become home to countless animals. It has, among other things, a species-rich fish population. With appropriate permission, fishing is also permitted in the Hassel Vorsperre. However, any additional activities for recreational purposes of any kind as well as water sports use of the reservoir are prohibited.
A six kilometer long circular hiking trail leads around the Hasselvorsperre reservoir. On the way you will pass several viewpoints. A section of the path on the west bank belongs to the southern route of the Harzer Hexenstieg. A good starting point for the hike around the lake is the parking lot on the Hassel north of the "Hagenmühle" on the northwestern outskirts of Hasselfelde.