Lahn basin

The Lahn () is a , right (or eastern) tributary of the Rhine in Germany. Its course passes through the federal states of North Rhine-Westphalia (23.0 km), Hesse (165.6 km), and Rhineland-Palatinate (57.0 km).

The Wiesensee () was an artificial lake, dammed up in 1971, in the Westerwald low mountain range. The lake covered about 80 hectares and lied in the area of Stahlhofen am Wiesensee's various centres on the lake's west shore, and Pottum on the north shore in the Westerwaldkreis. The community of Winnen borderd on the lake to the southeast. The lake was a nature conservation area, and only parts of the water surface were open for recreational use.