Blagdon Lake

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Blagdon Lake
Blagdonlake2.jpg
Location Chew Valley, Somerset
Coordinates 51°20′04″N 2°41′51″W / 51.33431°N 2.69757°W / 51.33431; -2.69757Coordinates: 51°20′04″N 2°41′51″W / 51.33431°N 2.69757°W / 51.33431; -2.69757
Type reservoir
Basin countries United Kingdom
Surface area 440 acres (180 ha)
Average depth 14 ft (4.3 m)
Max. depth 42 ft (13 m)
Water volume 8,456 million litres

Blagdon Lake ST515597 lies in the Chew Valley at the northern edge of the Mendip Hills, approximately 10 mi (16 km) south of Bristol, England. The lake was created by Bristol Water (Bristol Waterworks Company as it was known then), when it dammed the River Yeo, starting construction in 1891 and completing this in 1899. The Wrington Vale Light Railway was constructed primarily to bring building materials for the lake.

The lake still provides drinking water, but also acts as a fishing lake and nature reserve. The original suction tanks are now used for trout rearing.

The pumping station originally contained four steam engines, which have now been replaced by electric pumps. Two of the steam engines have been preserved, with one in working order as part of the visitor centre which also includes educational facilities for children.

Reservoir[edit]

The lake, which was originally called the Yeo reservoir, covers 440 acres (180 ha). The lake is relatively shallow, with an average depth of 14 ft (4.3 m) and only 42 ft (13 m) at its deepest point near the dam (west end of the lake). The eastern end is the shallowest where the River Yeo enters.[1] When full it contains 8,456 million litres and supplies 9,547 million litres of water each year, and works closely with its larger neighbour Chew Valley Lake.

Dam[edit]

The dam extends 175 ft (53 m) below ground to the solid rock underlying the valley. It was built of puddled clay with a central concrete core and faced with granite on the lake side. A 24-inch (610 mm) diameter pipe through the dam leads to the pumping station while a larger one is used to remove silt collecting against the dam. A flow of water is maintained in the River Yeo through a compensation channel and an overflow weir and spillway take flood water downstream.

Blagdon Lake Pumping station and Visitor Centre[edit]

Blagdon pumping station
Blagdon Lake from Blagdon Village

Blagdon Pumping Station and Visitor Centre includes science and environment exhibits and hands-on displays as well as a room dedicated to the charity WaterAid. One of the two steam driven beam engines is still working occasionally. Outside this is space for picnics and a nature trail.

When the lake first opened there were four Woolf compound rotative beam pumping engines, housed in two separate buildings. They were built by Glenfield & Kennedy of Kilmarnock between 1900 and 1905. The engine's beam is 34 ft (10.36 m) long and weighs 17 tons. The flywheel is 20 ft (6.10 m) in diameter and weighs 20 tons, having a crank throw of 3.5 ft (1.07 m). Each beam engine had an output of 170 horsepower (130 kW) at 17 rpm. The high-pressure cylinders, 21 inches (53.3 cm) in diameter and 3.25 ft (0.99 m) stroke, were supplied by steam from horizontal Lancashire-type twin flue boilers with Green's economisers at 100 pounds per square inch (6.9 bar). The low-pressure cylinder was 34 inches (86.4 cm) in diameter and has a 7 ft (2.13 m) stroke. Three engines with a fourth on standby could pump water at a rate of 7.5 million imperial gallons (34,000 m3) per day, whilst the boilers consumed 8.5 tons of coal per day. A mechanical efficiency of 90% was claimed, the 30 inches (76.2 cm) diameter pump bucket, 3.5 ft (1.07 m) strike and plunger diameter of 21 inches (53.34 cm) gave a pump output of 107 imperial gallons (490 l) per stroke. They ran until 1949, when two engines from the north engine house were replaced by electric pumps.[2]

In 1984 it was decided to preserve the two remaining engines and incorporate them as the central feature in the Visitor Centre, including a Museum in the old boiler house, which opened in 1988 and attracts over 30,000 visitors a year. The pumping station is now a Grade II listed building.[3]

Fishing[edit]

The lake is well known for trout fishing from its banks and the fleet of 18 rowing boats for hire. The suction tanks which originally supplied water to the steam boilers are now used as rearing pools for the fish before they are transferred into the lake. On average 50,000 trout are reared at Blagdon each year by Bristol Water to stock this and surrounding lakes such as Chew Valley Lake and the Barrow Tanks.

Ecology[edit]

Blagdon Lake from the A368 at Ubley

Blagdon Lake is designated a Site of Special Scientific Interest (SSSI) of 212.7 hectares, notified in 1971.[4] largely because of the variety of species and habitats.

A variety of water birds can be seen around the lake including; great crested grebe (Podiceps cristatus) and little grebe (Tachybaptus ruficollis), cormorant (Phalacrocoracidae), mute swan (Cygnus olor), Canada goose (Branta canadensis), duck (Anatidae), shoveller (Anas clypeata) and gadwall (Anas strepera).[5] Common buzzard (Buteo buteo) can be seen on the surrounding hills and both Eurasian sparrowhawk (Accipiter nisus) and kestrel breed. Occasional visitors include; passage osprey, goshawk (Accipiter gentilis), Eurasian hobby (Falco subbuteo), nuthatch and great spotted woodpecker (Dendrocopos major). The ruddy darter dragonfly (Sympetrum sanguineum) can also be seen.

A variety of orchids including green-winged orchid (Anacamptis morio) and southern marsh-orchids can be seen on the borders of the lake. In the wood at the western end of the lake there are populations of badgers, roe deer (Capreolus capreolus) and foxes.

References[edit]

  1. ^ "Blagdon Lake". Bristol Waters. Archived from the original on 2006-05-07. Retrieved 2006-07-08. 
  2. ^ "Blagdon Pumping Station visit". Histalec News. Retrieved 2010-10-04. 
  3. ^ "Blagdon Pumping Station". Images of England. Retrieved 2006-05-09. 
  4. ^ "Blagdon Lake". English Nature's SSSI Information. Retrieved 2006-07-07. 
  5. ^ "Blagdon Lake". Somerset Ornithological Society. Retrieved 2010-10-04. 

Bibliography[edit]

  • Janes, Rowland (ed) (1987). The Natural History of the Chew Valley. ISBN 0-9545125-0-2. 

Gallery[edit]

External links[edit]