is reliant on other tributaries in order to be able to supply drinking water. The Oker-Grane Tunnel was built in the period from 1968 to 1970. Stilling basin The stilling basin lies about 3 km below the dam of the Oker Reservoir and about 2 km below the Romkerhalle power station. It is furnished with a gravity dam which has a height of 18 metres. The stilling basin can store up to 204,000 m³ of water and its main purpose is to regulate the water level downstream. There is no power station immediately below the dam wall, however it services several smaller power station on the Oker as far as the northern edge of the Harz. Like the Oker Reservoir, in calm weather conditions, it forms a very smooth water surface which reflects the surrounding countryside very clearly. Because of the sheltered location of the stilling basin, this phenomenon occurs very frequently. Sewage In order not to pollute the water in the reservoir unnecessarily, sewage from Altenau and Schulenberg is led away in a separate pipe around the Oker Reservoir to the Goslar-Oker sewage farm. See also List of dams in the Harz List of reservoirs and dams in Germany References Sources External links Harz waterworks (with current dam data) Harz-Life: The Oker Dam Dams in Lower Saxony Dams in the Harz Dams completed in 1956