Start and finish: parking lot at the Wahnbachtalsperre, Siegburg-Seligenthal On the dam trail, hikers often experience the wonderful nature around the Wahnbach dam on mostly natural paths. In many places you can enjoy views far beyond the dam. Demanding, sometimes narrow and often historic hiking trails lead hikers through numerous sieves and over wooded ridges. A mill, two restaurants and two courtyards have been flooded since 1958. 5.8 km long, up to 124 m deep and filled with up to 43.18 million cubic meters of water, the Wahnbachtalsperre supplies around 800,000 people with drinking water.