The reservoir has a total capacity of approximately 20 million cubic meters of water.
During the Second World War, the dam was targeted by Allied bombing raids but suffered only minor structural damage compared to the nearby Edersee dam.
The Diemelsee was one of the first reservoirs in Germany to be developed with a primary focus on both flood protection and hydroelectric power.
The reservoir creates a state border between the federal states of Hesse and North Rhine-Westphalia.
The structure is classified as a historical technical monument due to its early 20th-century masonry engineering.
The Diemeltalsperre is a masonry gravity dam constructed between 1912 and 1920 to regulate water levels for the Weser river and support power generation. The wall stands 42 meters high and spans 194 meters across the Diemel valley in the Sauerland region. It impounds the Diemelsee reservoir, which serves as a major hub for regional water sports and recreational activities. The structure is built from local quarry stone, a characteristic aesthetic choice for German dams of the early 20th century. Visitors can walk directly across the top of the dam to view both the reservoir side and the steep drop-off to the valley floor below. It remains a functional site managed by the Wasserstraßen- und Schifffahrtsverwaltung des Bundes. The surrounding landscape features densely forested hills typical of the Upland region.
The center of the dam wall looking toward the main body of the reservoir.
Walk across the dam wall during sunset for optimal lighting on the water surface.
Combine your visit with the Uplandsteig hiking trail, which offers elevated viewpoints of the reservoir.
Bring polarized sunglasses to reduce glare when looking down from the dam wall into the clear water.
Attempting to swim directly adjacent to the dam wall, as this is strictly prohibited for safety and technical reasons.
Stay within designated pedestrian paths on the dam wall; do not climb on the protective barriers.
