Data of the Diemel dam
| Reservoir volume | 19.9 million m³ |
| at full damming | 376,20 m above sea level |
| Length | approx. 4 km upstream Diemel |
| approx. 3,1 km Itter upstream | |
| Max. Depth | 34,20 km |
| Water surface | approx. 1.65 m² |
The water is mainly fed by the inflows of the Itter and Diemel, with the Itter providing the largest inflow. The catchment area covers a total of 104 km². The discharge for a 1,000-year flood was designed in 1998 with 160m³/sec.
Data of the Diemel dam
| Construction period | 1912 to 1914 and 1919 to 1924 |
| Type of construction | Curved gravity dam (diabase rubble masonry) |
| K-radius | approx. 250 m |
| Wall height | approx. 42 m |
| Crown length | approx. 194 m |
| Crown width | approx. 7 m |
| Bottom length | approx. 90 m |
| Invert width | approx. 31 m |
In order to increase the safety standard in accordance with DIN 19700, a basic rehabilitation with tunnel-shaped inspection walkway was carried out from November 1995 to December 1997 (1998). The total costs for this amounted to about DM 20 million.
Operating equipment (2 bottom outlet pipes)
The pipe on the left slope with a diameter of 135 cm and a flow rate of 30 m³/sec. serves to relieve the reservoir contents in case of need. By means of reducers the flow rate can be reduced to 10 m³/sec., 3 m³/sec. or 1 m³/sec.
Equalizing basin
| Length | approx. 350 m |
| Width in the middle | approx. 80 m |
| Content | approx. 65,000 m³ |
| at full damming | 341.50 m above sea level |