Planning for the reservoir started in the 1960s with construction of the 35m-high dam starting in 1979. The reservoir is filled by pumping water from the River Derwent about 10.5 Kilometres (6.5 miles) away. This involved constructing tunnels, through the intervening hills, through which water is either pumped into the reservoir, at times of high river flow, and released back down the same pipe to the river, at times of low flow in the river. This enabled the continued abstraction of water during periods of drought from the river Derwent at Little Eaton. River water abstracted at Little Eaton is Treated at the nearby works to supply drinking water to Derby and also supplies raw water to Church Wilne Reservoir and Water Treatment works. The latter supplies drinking water to Nottingham.

From Wiki: In 1984 there was a partial collapse of the dam prior to its filling. The dam was subsequently completely removed before construction of a new dam commenced in 1989. The finished reservoir was opened by Queen Elizabeth II in 1992.