The reservoir is the biggest man-made reservoir in Europe and was constructed between 1975 and 1981 and opened in 1982 by the Queen. This period includes the 2 years it took the valley to flood after construction was finished. It was designed for Northumbria Water by Sir Frederick Gibberd and Partners and the consulting engineers were Babtie Shaw and Morton.
The area is known as Kielder Water and has become not only a means of regulating and storing the waters of the Tyne but a popular tourist attraction. The reservoir was built because the demand for water by industry on Tyne, Wear and Tees was forecast (in the 1960s) to exceed supply. Not without controversy, the scheme was approved by Parliament in 1974. A few houses were submerged together with a section of road and part of the former railway and there is a smaller reservoir at Bakethin at the western end to control water levels there. A new road has been built around the perimeter and there are visitor centres at Leaplish, Tower Knowe and Kielder.The growth of the forest and other vegetation has allowed the reservoir to blend into the surrounding countryside over the years. Although not included in the Ferries section, a boat is operated in summer to ferry people to various points on the reservoir.