| Obersee | |
| Coordinates: | 50.6°N 6.389°W |
| Location: | Borough of Aachen, North Rhine-Westphalia (Germany) |
| Construction Began: | ?–1959 |
| Dam Crosses: | Rur, Urft |
| Dam Height Thalweg: | 27 m |
| Dam Height Foundation: | 33 m |
| Dam Length: | 280 m |
| Dam Width Crest: | 14.0 m |
| Dam Width Base: | 135 m |
| Dam Curve Radius: | --> |
| Dam Volume: | 320,000 m3 |
| Res Capacity Total: | 23 M m3 |
| Res Capacity Active: | 17.9 or 20.8 M m3 |
| Res Max Length: | – 4.8 Rur river km (nur Obersee) – 5.15 Rur river km (Obersee and pre-dam) – 13.4 km (to the head of the reservoir) |
The Obersee near Simmerath in the borough of Aachen is the main forebay of the Rur Reservoir on the River Rur in the Eifel mountains of Germany. Its barrier is the Paulushofdamm. The reservoir, like that of the Rur Dam, belongs to the Eifel-Rur Water Company (Wasserverband Eifel-Rur). The reservoir provides drinking water.
The dam system, which comprises the Paulushofdamm and Obersee, lies in the Rur Eifel, a part of the North Eifel, southwest of the Kermeter, north of the Dreiborn Plateau and east of the Monschau Hedge Land near Simmerath (borough of Aachen). It is located immediately below the Urft Dam, which impounds the waters of the Urft that flow from the east to create the Urft Reservoir, and immediately above the Rur Dam which impounds the waters of the Rur to form the Rur Reservoir. While the dam belongs to the High Fens-Eifel Nature Park, the large eastern arm of the Obersee in the north lies within the Eifel National Park.