Diemelsee

Diemelsee, Diemel Reservoir Diemelstausee, Diemeltalsperre
The Diemel Dam: dam and reservoir, compensating basin (Ausgleichsweiher) and power station. Foreground: the village of Helminghausen. Left: the Eisenberg
Location	Waldeck-Frankenberg (HE), Hochsauerlandkreis (NW)
Coordinates	51°22′20″N 8°43′26″E / 51.37222°N 8.72389°E / 51.37222; 8.72389
Construction began	1912 to 1914 and 1919 to 1923[1]
Dam and spillways
Impounds	Diemel, Itter
Height (foundation)	42 m[1]
Height (thalweg)	36.2 m[2]
Length	194 m[1]
Width (crest)	7 m[1]
Width (base)	31 m[2]
Dam volume	72,000 m³[2]
Spillway capacity	113 m³/s
Reservoir
Total capacity	21.75 M m³
Active capacity	19.9 M m³[1]
Catchment area	103 km²
Surface area	1.65 km²[1]
Maximum length	4 km (Diemel arm), 3.1 km (Itter arm)
Maximum width	300 m
Normal elevation	376.2 m above sea level (NHN)
Installed capacity	1.04 MW

The Diemelsee or Diemel Reservoir (German: Diemelstausee) is a reservoir with a surface area of 1.65 km²^[1] and about capacity of 19.9 million m³^[1] on the River Diemel in the counties of Waldeck-Frankenberg in North Hesse, and Hochsauerlandkreis, Westphalia, Germany.

It is part of the Diemeltalsperre hydropower system (DiT)^[3] comprising the Diemel Dam, the equalizing basin, the power plant and the reservoir itself, owned by the Federal Waterway and Navigation Authority and managed by its Hann. Münden office. The Diemel Reservoir, along with the Edersee is part of the water regulation structure in the catchment area of the River Weser.