For the Pumpspeicherwerk Rönkhausen, a 1 million m³ reservoir was built on the Dahlberg between 1964 and 1969, and a further 1.3 million m³ reservoir was built 270 meters lower down in the Glinge valley. The connection is made by a 936-meter-long pressure tunnel with a diameter of 3.60 meters. A special feature are the two pumps that generate electricity by reversing the direction of flow. The plant serves to cover peak loads in electricity consumption. Cheap nighttime electricity is used to pump water from the lower basin in the Glingetal to the Dahlberg, thus generating electricity again when the peak loads occur during the day.