During the Second World War, the reservoir was used by pilots of the 617 Squadron for practising the low-level flights needed for Operation Chastise (commonly known as the “Dam Busters” raids), due to its similarity to the German dams.
Today there is a commemorative plaque to 617 Squadron on the dam, and one of the towers on the dam houses the Derwent Valley Museum.
The exhibition, owned and run by Vic Hallam, tells the tale of Squadron 617 and its training for Operation Chastise and also has a display on the history of the Derwent valley and the lost villages of Derwent and Ashopton.
Occasional flypasts of the Battle of Britain Memorial Flight at the reservoir are also staged to commemorate the events during the war.
In September 2014, a unique and never to be repeated flypast took place with the two remaining airworthy Lancasters, one from the Battle of Britain Memorial Flight, and one from Canada, flying three passes in formation.
Derwent Reservoir is the middle of three reservoirs in the Upper Derwent Valley in the northeast of Derbyshire, England. It lies approximately 10 miles (16 km) from Glossop and 10 miles (16 km) from Sheffield. The River Derwent flows first through Howden Reservoir, then Derwent Reservoir and finally through Ladybower Reservoir. Between them they provide practically all of Derbyshire’s water, as well as to a large part of South Yorkshire and as far afield as Nottingham and Leicester.
Derwent Reservoir is around 1.5 miles (2.4 km) in length, running broadly north–south, with Howden Dam at the northern end and Derwent Dam at the south. A small island lies near the Howden Dam. The Abbey Brook flows into the reservoir from the east.
At its full capacity the reservoir covers an area of 70.8 hectares (175 acres) and at its deepest point is 34.7 metres (114 ft) deep