Blelham Tarn

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Blelham Tarn
A derelict boathouse extending out onto a lake
The boathouse on the tarn in 2007
Blelham Tarn is located in the Lake District
Blelham Tarn
Blelham Tarn
LocationCumbria
Coordinates54°23′44″N 2°58′41″W / 54.39556°N 2.97806°W / 54.39556; -2.97806Coordinates: 54°23′44″N 2°58′41″W / 54.39556°N 2.97806°W / 54.39556; -2.97806
Typenatural
Etymologydark blue pool[1]
Primary outflows
Max. length0.66 km (0.41 mi)[2]
Max. width0.257 km (0.160 mi)[1]
Surface area11 ha (27 acres)[2]
Average depth6.8 m (22 ft)[2]
Max. depth14.5 m (48 ft)[2]
Water volume717,829 cubic metres (582 acre⋅ft)[2]
Residence time50 days[3]
Surface elevation47 m (154 ft)[2]

Blelham Tarn is a large valley tarn in the Lake District of England, to the north of the hill Latterbarrow. The settlements of , Low Wray and High Wray are close by. The tarn is drained to the northeast by the short into Windermere. This beck was previously straightened and lowered.[4] Fish species in the tarn include brown trout, eel, perch, pike and roach,[5] much of the tarn shore is reedbed and waterfowl present can include great crested grebe, whooper swan and golden-eye.[6]

The tarn is regularly monitored by the United Kingdom Lake Ecological Observatory Network and is characterised as eutrophic and monomictic[3] and has suffered from agricultural water pollution[7] with large quantities of blue-green algae in the summer.[5] The lake temperature at various depths varied over the period July 2012 to November 2014 between 2 and 25 Celsius as the air temperature (3 m above the surface) varied between -3 and 22 Celsius. Over the same period the pH varied from 6.4 to 9.8 and the dissolved oxygen ranged from 7 to 14 mg/l.[8]

Blelham Tarn and Bog, with a total area of 49 hectares, is designated a site of special scientific interest[9] and Blelham Bog is designated a National Nature Reserve[6] The bog contains various species of sphagnum moss, bog myrtle, cotton-grass and the white-beaked sedge; and rare caddis-flies and vertigo lilljeborgi.[6]

References[]

  1. ^ a b Blelham Tarn
  2. ^ a b c d e f "Blelham Tarn Water Body ID 29270". UK Lakes Detail. NERC Centre for Ecology and Hydrology. Archived from the original on 11 June 2016. Retrieved 23 May 2016.
  3. ^ a b UKLEON: United Kingdom Lake Ecological Observatory Network
  4. ^ Blelham Tarn & Bog - Unit 2
  5. ^ a b Blelham Tarn
  6. ^ a b c Cumbria's National Nature Reserves
  7. ^ Blelham Tarn & Bog - Unit 6[permanent dead link]
  8. ^ Data from the UK Lake Ecological Observatory Network
  9. ^ SSSI units for Blelham Tarn & Bog[permanent dead link]
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