The Ladybower Reservoir is the lowest of three reservoirs in the Upper Derwent Valley in Derbyshire, England. The River Derwent initially flows through Howden Reservoir, then Derwent Reservoir, and finally through Ladybower Reservoir.

Water is treated at Bamford water treatment works by Severn Trent Water. Treated water flows down the Derwent Valley Aqueduct to supply clean water to towns and cities in the East Midlands of England.

The building of the dam wall was undertaken by the Scottish company of Richard Baillie and Sons, while the two viaducts, namely, Ashopton and Ladybower which were needed to carry the trunk roads over the reservior, were built by the London firm of Holloways. Both firms encountered mounting problems when World War Two broke out in 1939 making labour and raw materials scarce.

The upper dams were used during World War II for practice by 617 Squadron prior to the Dambusters raid on German dams. Occasional flypasts of the Battle of Britain Memorial Flight are staged to comemmorate this.

The Ladybower was built and filled between 1935 and 1945. The opening ceremony for the reservoir was carried out on Tuesday September 25th 1945 by King George VI accompanied by Queen Elizabeth, later to become the Queen Mother.The building of the reservoir resulted in the 'drowning' of the village of Derwent (including Derwent Woodlands church and Derwent Hall) Much of the structure of the village was still visible during a dry summer some fourteen years later.