Blagdon Lake
{{Short description|Lake in the United Kingdom}}
{{Good article}}
{{Use dmy dates|date=July 2015}}
{{Use British English|date=February 2023}}
{{Infobox body of water
| name = Blagdon Lake
| image = Blagdonlake2.jpg
| alt = Photo of the lake surrounded by trees
| caption =
| image_bathymetry =
| caption_bathymetry =
| location = Blagdon, Somerset
| coords = {{Coord|51.3350|N|2.6975|W|region:GB_type:waterbody|format=dms|display=inline,title}}
| type = reservoir
| inflow = River Yeo
| pushpin_map = Somerset
| pushpin_map_alt = Location in Somerset
| outflow = River Yeo
| catchment = {{cvt|2144|ha}}
| basin_countries = United Kingdom
| length =
| width =
| area = {{cvt|440|acre}}
| depth = {{cvt|14|ft}}
| max-depth = {{cvt|42|ft}}
| volume = {{convert|8,456|e6L|acre.ft|abbr=out}}
| residence_time =
| shore =
| elevation =
| islands =
| cities =
}}
Blagdon Lake lies in a valley at the northern edge of the Mendip Hills, close to the village of Blagdon and approximately {{convert|10|mi}} 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 1898, to designs by Charles Hawksley, and completing this in 1905. The Wrington Vale Light Railway was constructed primarily to bring building materials for the lake.
The reservoir was formed by the construction of a dam and provided water to the pumping station which originally contained four Woolf compound rotative beam pumping engines, built by Glenfield & Kennedy of Kilmarnock, which have now been replaced by electric pumps.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. The pumping station is now a Grade II* listed building.
The {{convert|8,456,000,000|L|adj=on}} lake still provides {{cvt|9,547,000,000|L}} of drinking water each year, but also acts as a fishing lake. It provides a habitat for a range of flora and fauna and is a Site of Special Scientific Interest. The original suction tanks, which formed the water supply for the steam boilers powering the pumping engines, are now used for trout rearing.
Reservoir
The lake, which was originally called the Yeo reservoir, covers {{convert|440|acre|ha}}.{{cite web |title=Blagdon Lake |url=http://www.bristolwaterfisheries.co.uk/lakes/blagdon-lake/ |publisher=Bristol Water |access-date=5 July 2015 |url-status=live |archive-url=https://web.archive.org/web/20150715125323/http://www.bristolwaterfisheries.co.uk/lakes/blagdon-lake |archive-date=15 July 2015 |df=dmy-all}} The River Yeo rises in the centre of Compton Martin village, from there it flows past the village of Ubley and enters Blagdon Lake. From the lake the river flows south of Wrington and Iwood, where there were once a series of watermills along its banks. Its route then takes it around the northern outskirts of Congresbury, and across the North Somerset Levels roughly parallel to the A370 road, past the site of a Roman villa before crossing under the M5 motorway and emptying into the Severn Estuary in Woodspring Bay, downstream from Clevedon and west of the village of Kingston Seymour. The watershed catchment area of the reservoir is {{convert|2144|ha}}.
File:Blagdon and chew from air arp.jpg in the distance.]]
The construction of the reservoir was approved by acts of parliament in 1888 and 1889 as part of a plan to provide drinking water to Bristol, supplementing Barrow Gurney Reservoirs and the "line of works" pipe which carries water from the Mendip Hills. Construction required the provision of sewers to local villages to avoid contamination of the reservoir.{{cite news |title=Bristol's Water Supply: The Yeo Valley Reservoir |url=http://www.britishnewspaperarchive.co.uk/viewer/bl/0000264/19020124/056/0009 |access-date=5 July 2015 |work=Western Daily Press |date=24 January 1902 |via=British Newspaper Archive |url-access=subscription }} The work was designed by Charles Hawksley.{{NHLE|desc=Waterworks at Blagdon: Pumping Station with Receiving Tanks|num=1320936|access-date=5 July 2015}} In conjunction with the construction work the Wrington Vale Light Railway was established connecting Blagdon with Congresbury on the Cheddar Valley Line and Yatton on the main Bristol to Exeter line.{{cite web |title=History of Blagdon |url=http://www.bristolwater.co.uk/aboutUs/historyBlagdon.asp |publisher=Bristol Water |access-date=5 July 2015 |archive-url=https://web.archive.org/web/20120218045530/http://www.bristolwater.co.uk/aboutUs/historyBlagdon.asp |archive-date=18 February 2012}} In addition to carrying construction materials for the reservoir and pumping station it also provided passenger services. Later the railway was used to bring coal for the pumps. Passenger traffic ceased in 1931 and the line to Blagdon closed completely in 1950.{{cite book |last1=Maggs |first1=Colin Gerald |title=The Wrington Vale Light Railway |date=2004 |publisher=The Oakwood Press |isbn=978-0-85361-620-7}}
The lake is relatively shallow, with an average depth of {{cvt|14|ft|m}} and only {{cvt|42|ft|m}} at its deepest point near the dam at the west end of the lake.{{cite news |last1=Brooke |first1=Gerry |title=Footsteps into History — Blagdon |url=http://www.bristolpost.co.uk/Footsteps-History-dam-fine-place-visit/story-11268406-detail/story.html |access-date=5 July 2015 |work=Bristol Post |date=27 July 2009 |url-status=dead |archive-url=https://web.archive.org/web/20150714135532/http://www.bristolpost.co.uk/Footsteps-History-dam-fine-place-visit/story-11268406-detail/story.html |archive-date=14 July 2015 |df=dmy-all}} The eastern end is the shallowest where the River Yeo enters.{{cite web |title=Blagdon Lake |work=Bristol Waters |url=http://eis.bris.ac.uk/~cckhrb/BW/blagdon.htm |access-date=8 July 2006 |archive-url=https://web.archive.org/web/20060507052535/http://eis.bris.ac.uk/~cckhrb/BW/blagdon.htm |archive-date=7 May 2006}} It is a hard water area with high mineral content that is vulnerable to eutrophication in the summer, that can cause algal blooms, with transient water layers. As a result, a research programme has been established to observe and measure the limnology of the lake.{{cite journal |last1=Wilson |first1=R. S. |last2=Sleigh |first2=M. A. |last3=Maxwell |first3=T. R. A. |last4=Mance |first4=G. |last5=Milne |first5=R. A. |title=Physical and Chemical Aspects of Chew Valley and Blagdon Lakes, Two Eutrophic Reservoirs in North Somerset, England |journal=Freshwater Biology |date=2006 |volume=4 |issue=5 |pages=357–377 |doi=10.1111/j.1365-2427.1975.tb01760.x |df=dmy-all}} When full it contains {{convert|8,456,000,000|L}} and supplies {{convert|9,547,000,000|L}} of water each year. Water can also be taken from its larger neighbour Chew Valley Lake to balance the supply.{{cite web |title=Sources |url=http://www.bristolwater.co.uk/wp/wp-content/uploads/2013/03/Sources.pdf |publisher=Bristol Water |access-date=5 July 2015 |archive-url=https://web.archive.org/web/20150706134822/http://www.bristolwater.co.uk/wp/wp-content/uploads/2013/03/Sources.pdf |archive-date=6 July 2015 |url-status=dead}}
=Dam=
The dam extends {{cvt|175|ft|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 {{convert|24|in|mm|adj=mid|-diameter}} pipe through the dam leads to the pumping station while a larger one is used to remove silt collecting against the dam.{{cite web |title=Blagdon Visitor Centre |url=http://www.bristolwater.co.uk/wp/wp-content/uploads/2013/03/blagdonvisitorcentre.pdf |publisher=Bristol Water |access-date=5 July 2015 |archive-url=https://web.archive.org/web/20150923194614/http://www.bristolwater.co.uk/wp/wp-content/uploads/2013/03/blagdonvisitorcentre.pdf |archive-date=23 September 2015 |url-status=dead}} A flow of water is maintained in the River Yeo through a compensation channel and an overflow weir and spillway take flood water downstream.
Pumping station and Visitor Centre
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.{{cite web |title=Discover Wood Trail |url=http://www.bristolwater.co.uk/wp/wp-content/uploads/2013/04/onthetrail.pdf |publisher=Bristol Water |access-date=5 July 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150923194619/http://www.bristolwater.co.uk/wp/wp-content/uploads/2013/04/onthetrail.pdf |archive-date=23 September 2015 |df=dmy-all}}
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 {{cvt|34|ft|m|2}} long and weighs 17 tons. The flywheel is {{cvt|20|ft|m|2}} in diameter and weighs 20 tons, having a crank throw of {{cvt|3.5|ft|m|2}}. Each beam engine had an output of {{convert|170|hp|kW}} at 17 rpm. The high-pressure cylinders, {{convert|21|in|cm|1}} in diameter and with a {{cvt|3.25|ft|m|2}} stroke, were supplied by steam from horizontal Lancashire-type twin flue boilers with Green's economisers at {{convert|100|psi|bar}}. The low-pressure cylinder was {{convert|34|in|cm|1}} in diameter and has a {{cvt|7|ft|m|2}} stroke. Three engines with a fourth on standby could pump water at a rate of {{convert|7.5|e6impgal|m3}} per day, whilst the boilers consumed 8.5 tons of coal per day. A mechanical efficiency of 90% was claimed, the {{convert|30|in|cm|1|adj=on}} diameter pump bucket, {{cvt|3.5|ft|m|2|adj=on}} strike and plunger diameter of {{convert|21|in|cm|1}} gave a pump output of {{convert|107|impgal|L}} per stroke. They ran until 1949, when two engines from the north engine house were replaced by electric pumps.{{cite web |title=Blagdon Pumping Station visit |work=Histalec News |url=http://www.swehs.co.uk/tactive/_X98-2.html?zoom_highlight=Blagdon#item08 |access-date=5 July 2015 |url-status=live |archive-url=https://web.archive.org/web/20150705214349/http://www.swehs.co.uk/tactive/_X98-2.html?zoom_highlight=Blagdon#item08 |archive-date=5 July 2015 |df=dmy-all}} In 1950 automatic shutdown equipment was installed to prevent damage in the event of a burst main or overloading of the new electric pumps. This meant that it was no longer essential to have staff on site 24 hours a day.{{cite book |last1=Hodgson |first1=Alan |title=The Story of the Bristol Waterworks Company 1939–1991 |date=1991 |page=20 |asin=B001KMZF9I}} The decorative chimney was shortened in the 1960s. In 2014 new split-case vertical pumps and various other new equipment was installed to replace those installed in the 1940s and 1950s.{{cite web |last1=King |first1=Matthew |last2=Fenwick |first2=Andrew |last3=Davis |first3=Ben |title=Blagdon Pumping Station and Intake Upgrade |url=http://www.waterprojectsonline.com/case_studies/2014/Bristol_Blagdon_2014.pdf |publisher=Water Projects Online |access-date=5 July 2015 |url-status=live |archive-url=https://web.archive.org/web/20150706172039/http://www.waterprojectsonline.com/case_studies/2014/Bristol_Blagdon_2014.pdf |archive-date=6 July 2015 |df=dmy-all}}
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.{{cite web |last1=Wallis |first1=Geoffrey |title=Keeping The Wheels Turning |url=http://www.buildingconservation.com/articles/wheelturn/wheelturn.htm |publisher=Building Conservation |access-date=5 July 2015 |url-status=live |archive-url=https://web.archive.org/web/20150923195216/http://www.buildingconservation.com/articles/wheelturn/wheelturn.htm |archive-date=23 September 2015 |df=dmy-all}} The flywheel is now driven by an electric motor.{{cite web |title=Industrial Conservation Works, Blagdon Beam Engine |url=http://www.dorothearestorations.com/case-studies/blagdon-beam-engine |publisher=Dorothea Restorations |access-date=5 July 2015 |archive-date=6 July 2015 |archive-url=https://web.archive.org/web/20150706020912/http://www.dorothearestorations.com/case-studies/blagdon-beam-engine |url-status=live }} The pumping station is now a Grade II* listed building, while the Gothic-style meter house is Grade II listed and used as a bat sanctuary.{{NHLE|desc=Waterworks at Blagdon: former meter house|num=1424249|access-date=5 July 2015}}
Fishing
File:Nymph patterns innovated by Dr Bell of Wrington.jpeg
File:Blagdon Lake showing bank features.jpg
Blagdon Lake first opened as a trout fishery in 1904.{{Cite web |url=http://webdatauk.wixsite.com/dr-bell/history |title=History Page of Dr Bell of Wrington |access-date=3 September 2018 |archive-date=3 September 2018 |archive-url=https://web.archive.org/web/20180903114947/http://webdatauk.wixsite.com/dr-bell/history |url-status=live }} 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 for the pumping engines 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.{{cite web |title=Blagdon Lake |url=http://www.wheretofish.co.uk/blagdon-lake-3904.html |publisher=Where to Fish |access-date=5 July 2015 |url-status=live |archive-url=https://web.archive.org/web/20150517044741/http://www.wheretofish.co.uk/blagdon-lake-3904.html |archive-date=17 May 2015 |df=dmy-all}}
Ecology
File:Moon over Blagdon Lake (geograph 3873857).jpg
Blagdon Lake is designated a Site of Special Scientific Interest (SSSI){{cite web |title=Blagdon Lake |url=http://www.mendiphillsaonb.org.uk/wp-content/uploads/2013/08/Blagdon-Lake-Walk-2.pdf |publisher=Mendip Hills AONB |access-date=5 July 2015 |url-status=live |archive-url=https://web.archive.org/web/20150706004251/http://www.mendiphillsaonb.org.uk/wp-content/uploads/2013/08/Blagdon-Lake-Walk-2.pdf |archive-date=6 July 2015 |df=dmy-all}} of {{convert|212.7|ha}}, created in 1971,{{cite web |title=Blagdon Lake |work=English Nature's SSSI Information |url=http://www.sssi.naturalengland.org.uk/citation/citation_photo/1000808.pdf |access-date=5 July 2015 |url-status=dead |archive-url=https://web.archive.org/web/20121024024716/http://www.sssi.naturalengland.org.uk/citation/citation_photo/1000808.pdf |archive-date=24 October 2012}} largely because of the variety of species and habitats. The area around the pumping station was laid out as an ornamental woodland which includes Scots pine, cedar, larch, spruce, oak, beech, chestnut, willow, lime, holly and maple. A variety of orchids including green-winged orchid (Anacamptis morio) and southern marsh-orchids can be seen on the borders of the lake.{{cite web |title=Blagdon Lake |url=http://www.somersetbirds.net/blagdon_lake.htm |publisher=Somerset Ornithological Society |access-date=5 July 2015 |archive-url=https://web.archive.org/web/20081230003953/http://www.somersetbirds.net/blagdon_lake.htm |archive-date=30 December 2008}}
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). Common buzzards (Buteo buteo) can be seen on the surrounding hills and both Eurasian sparrowhawk (Accipiter nisus) and kestrel breed. Occasional visitors include: osprey (Pandion haeliatis), goshawk (Accipiter gentilis), Eurasian hobby (Falco subbuteo), nuthatch and great spotted woodpecker (Dendrocopos major). The ruddy darter dragonfly (Sympetrum sanguineum) can also be seen. In the wood at the western end of the lake there are populations of badgers, roe deer (Capreolus capreolus) and foxes.{{cite web |title=Blagdon Lake |url=https://www.natureflip.com/blagdon-lake |publisher=Natureflip |access-date=5 July 2015 |date=2014-04-26}}
References
{{reflist|30em}}
External links
{{Commons category|Blagdon Lake}}
- [http://www.bristolwater.co.uk/leisure/blagdon-lake/ Blagdon Lake] with link to brochure about Blagdon Lake Pumping station and Visitor Centre
- [https://web.archive.org/web/20150327060311/http://www.bristolwater.co.uk/leisure/blagdon-lake/blagdon-visitor-centre/ Blagdon Visitor Centre] - Bristol Water official site
- [https://www.blagdonlakebirds.com/ Blagdon Lake Birds]
{{portalbar|Lakes}}
{{Bristol Reservoirs}}
{{Chew Valley}}
{{SSSIs Avon biological}}
{{Mendip Hills}}
{{authority control}}
Category:Grade II* listed buildings in North Somerset
Category:Drinking water reservoirs in England
Category:Sites of Special Scientific Interest in Avon
Category:Sites of Special Scientific Interest notified in 1971
Category:Reservoirs in Somerset
Category:Nature Conservation Review sites
Category:Wetland Sites of Special Scientific Interest
Category:Water supply pumping stations