Ladybower Reservoir

Ladybower Reservoir
Ladybower Reservoir from Bamford Edge (seen in the foreground); the wall can be seen in the bottom left and the Ashopton Viaduct in the top centre
Location	Upper Derwent Valley, Derbyshire
Coordinates	53°23′N 1°43′W / 53.383°N 1.717°W / 53.383; -1.717Coordinates: 53°23′N 1°43′W / 53.383°N 1.717°W / 53.383; -1.717
Lake type	reservoir
Primary inflows	River Ashop, River Derwent
Primary outflows	River Derwent
Catchment area	6,364 acres (2,575 ha)
Basin countries	United Kingdom
Max. length	2.5 mi (4.0 km)
Max. width	1,950 ft (590 m)
Surface area	210 ha (520 acres)
Average depth	95 ft (29 m)
Max. depth	135 ft (41 m)
Water volume	27,800,000 m3 (6.1×109 imp gal)
Shore length1	13 mi (21 km)
Surface elevation	668 ft (204 m)
References
1 Shore length is not a well-defined measure.

Ladybower Reservoir is a large Y-shaped reservoir, the lowest of three in the Upper Derwent Valley in Derbyshire, England. The River Ashop flows into the reservoir from the west; the River Derwent flows south, initially through Howden Reservoir, then Derwent Reservoir, and finally through Ladybower Reservoir.

The area is now a tourist attraction, with the Fairholmes visitors' centre located at the northern tip of Ladybower.

Ladybower was built between 1935 and 1943 by the Derwent Valley Water Board to supplement the other two reservoirs in supplying the water needs of the East Midlands. It took a further two years to fill (1945). The dam differs from the Howden Reservoir and Derwent Reservoir in that it is a clay-cored earth embankment, and not a solid masonry dam. Below the dam is a cut-off trench 180 feet (55 m) deep and 6 feet (1.8 m) wide filled with concrete, stretching 500 feet (150 m) into the hills each side, to stop water leaking round the dam. The dam wall was built by Richard Baillie and Sons, a Scottish company. The two viaducts, Ashopton and Ladybower, needed to carry the trunk roads over the reservoir were built by the London firm of Holloways, using a steel frame clad in concrete. The project was delayed when the Second World War broke out in 1939, making labour and raw materials scarce. But construction was continued due to the strategic importance of maintaining supplies. King George VI, accompanied by Queen Elizabeth, formally opened the reservoir on 25 September 1945.

During the 1990s the wall was raised and strengthened to reduce the risk of over-topping in a major flood. The original dam wall contains 100,000 tons of concrete, over one million tons of earth and 100,000 tons of clay for the core. The upstream face is stone faced. Materials were brought to the site on the Derwent Valley Water Board's own branch line and their sidings off the main line in the Hope Valley.