Harpener Teiche, Recreational lakes in Bochum-Nord and Bochum-Ost, Germany

The Harpener Teiche are two interconnected lakes located in Bochum-Nord and Bochum-Ost that have become a recreational area for the neighborhood. Both water bodies are surrounded by walking paths and rest areas where people can stop and observe the water and the surrounding landscape.

The ponds were dug as settling basins for the Robert Müser colliery, where coal slurry from the coal washing plant was left to settle. After the mine closed, its mine-water pumping station was expanded into one of three central stations for the Ruhr catchment, lifting water from a depth of 550 m. Since the renaturation of the Harpener Bach, the ponds are fed only by mine water, which is piped underground to the Ümminger See.

The city of Bochum laid out a Hochzeitswald (wedding forest) along the path, where couples plant a tree on their wedding day. Benches line the route, and the ponds are a spot for watching stock ducks, coots, great crested grebes and swans. The Bochum Botanical Society recorded rare species here in 2009, including the red kite, skylark and ant cricket.

The lakes can be reached from several entry points along Werner Straße, with paved pathways circling both water bodies for easy walking. The area is straightforward to explore on foot and offers plenty of spots to rest and take in the surroundings.

The ponds are fed mainly by mine water pumped from a depth of 550 metres, about 7.8 million cubic metres a year. It emerges at roughly 28 °C and carries up to 40 grams of chloride per litre, which tints the inflow milky and sometimes causes hydrogen sulphide odours. Hydrogen peroxide is added to reduce the smell, and heat exchangers use the warmth to heat two schools and the nearby fire station.