King George VI Reservoir

The King George VI Reservoir in England lies to the south of Stanwellmoor near Stanwell and Heathrow. The reservoir was opened in November 1947 and named after the then reigning monarch King George VI. It is owned by Thames Water.

The reservoir occupies 350 acres (1.4 km2) and holds 3493 million imperial gallons (15,880,000 m³). Its maximum height above the original ground level is 56 ft (17 m). Like the other Lower Thames reservoirs, it is of traditional earthen dam construction, with a puddled clay core supported by ballast embankments built from materials excavated on site. It is entirely man-made, as the area had no natural topographical features that could be dammed off to create a reservoir. To make inspecting the integrity of the reservoir easier, Thames Water maintains a commercial flock of sheep on the reservoir banks to keep the grass on the reservoir banks close-cropped.

The reservoir was completed in 1939 but was left empty due to the outbreak of the Second World War. It was reputed that a mock Clapham Junction railway station was built inside to confuse the Luftwaffe. The reservoir was used for fog dispersal experiments in the development of the FIDO landing system.

This reservoir and the adjacent Staines Reservoirs receive their input from the River Thames at Hythe End just above Bell Weir Lock. The Staines Aqueduct continues eastwards, passing the Water Treatment Works at Kempton Park, to supply the Water Treatment Works at Hampton. The other adjacent reservoir, Wraysbury Reservoir, is situated to the west on the other side of the M25.

The reservoir forms part of the Staines Moor Site of Special Scientific Interest. The reservoirs carry nationally important wintering populations of tufted ducks, pochard, goosander and goldeneye.