LOCH SHIEL

A southwestward view of the lake from its northern end Photo. Photo: A. Kurata  
 
 

A. LOCATION

  • Scotland, UK.
  • 56:51N, 5:30W; 4.5 m above sea level.
 

B. DESCRIPTION

    Of glacial origin, Loch Shiel is the fourth largest lake by length in Scotland and this is one whose water regime is among the least affected by man. The lake has a total length of 28.0 km - only exceeded by Lochs Awe, Ness and Lomond. Like Loch Awe, it is very narrow with a mean breadth which is only 2.5% of its total length. The main upper portion of the lake runs in a northeast/southwest direction, but about 8 km from the outflow the axis bends and the lower portion bends almost due west. The surface area of the lake is 19.6 km2: it has a mean depth of 40.5 m and a maximum one of 128.0 m. It contains a total volume of 892,500,000 m3.
    Like Loch Lomond, the northern end of Loch Shiel is much deeper than the southern end. The basin is essentially a single one, but there are a number of minor depressions here and there, two of them deeper than 120 m.
    Since the construction of the River Leven Barrage in Loch Lomond, only Loch Shiel has a natural outlet. Loch Awe is regulated by a barrage: Loch Ness is affected by the works associated with the Caledonian Canal and the short outlet channel from Loch Morar is influenced by a small hydro-electric scheme.
    Loch Shiel has very similar catchments to Loch Morar in many respects; moderate altitude, but steep slopes, very little arable ground and base-poor geology. The lake, therefore, is likely to be very nutrient poor (1, 2, 4, 10).
 

C. PHYSICAL DIMENSIONS (1, 2)

     
    Surface area [km2] 20
    Volume [km3] 0.9
    Maximum depth [m] 128.0
    Mean depth [m] 40.5
    Water level Unregulated
    Normal range of annual water level fluctuation [m] 2.0
    Length of shoreline [km] 77.6
    Residence time [yr] 1.4
    Catchment area [km2] 234
     
 

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL (2)
  • Bathymetric map:

    Fig. EUR-26-01.
  • Names of main islands: The area of island is 0.11 km2.
  • Number of outflowing rivers and channels (name): 1 (R. Shiel).
D2 CLIMATIC
  • Climatic data at Achnashellach (3)*
     
    Mean temp. [deg C]
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    2.8 3.2 5.2 6.9 10.1 12.4 13.8 13.6 11.6 8.7 5.7 4.1 8.2
    Precipitation [mm]
    232 177 127 156 93 114 148 150 189 234 196 242 2,058
    * 13-year mean.
     
  • Number of hours of bright sunshine: 1,374 hr yr-1.
     
 
  • Water temperature: Fig. EUR-26-02.

    Fig. EUR-26-02
    Water temperature [deg C](2).
 
  • Freezing period: Occasionally (2).
  • Mixing type: Monomictic (2).
 

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](6) November 1977 and Octber 1978: 5.1-8.0.

E2 pH (4)

     
    1977
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0-10 - - - - - - - - - - 6.2 6.3
    1978
    0-10 - 6.2 - 6.2 6.1 - - 6.1 - 6.2 - -
     
E6 CHLOROPHYLL CONCENTRATION [micro g l-1]: Fig. EUR-26-03.

    Fig. EUR-26-03
    Fluctuations in the concentration of chlorophyll a. Values refer to the integrated 0-10 m column at open water site (5).
E7 NITROGEN CONCENTRATION: Fig. EUR-26-04.

    Fig. EUR-26-04
    Fluctuations in the concentrations of NO3- and NO2-N in the uppermost 10 m of the water column (5).
E8 PHOSPHORUS CONCENTRATION (4)
  • PO4-P value [micro g l-1]

    • November 1977-October 1978: <10.
 

F. BIOLOGICAL FEATURES

F1 FLORA
  • Submerged macrophytes (6)

    • Littorella uniflora, Lobelia dortmanna, Isoetes lacustris.
  • Phytoplankton (5)

    • Rhizosolenia longiseta, R. eriensis, Tabellaria fenestrata, T. fenestrata var. asterionelloides, T. flocculosa, Cryptomonas erosa, C. ovata, Rhodomonas minuta.
F2 FAUNA
  • Zooplankton (7)

    • Bosmina coregoni, Polyphemus pediculus, Bythotrephes longimanus, Leptodora kindti, Diaptomus gracilis, Cyclops abyssorum, Diaphanosoma brachyurum, Holope:dium gibberum, Diaptomus laciniatus.
  • Benthos (8)

    • Stylaria lacustris, Lumbriculus variegatus, Ecdyonurus dispar, Leuctra hippopus, L. fusca, Chloroperla torrentium, Lepidostoma hirtum.
  • Fish (9)

    • Salmo salar, S. trutta, Anguilla anguilla, Gasterosteus aculeatus aculeatus, Platichthys flesus.
F4 BIOMASS (7)
  • Zooplankton: Fig. EUR-26-05.

    Fig. EUR-26-5
    The seasonal abundance of total zooplankton [1,000 individuals m-3].
 

G. SOCIO-ECONOMIC CONDITIONS (1)

G1 LAND USE IN THE CATCHMENT AREA
     
    Area[km2] [%]
    - Natural landscape
    Woody vegetation 36.9 15.8
    Rough 186.0 79.5
    - Agricultural land 3.3 1.4
    - Residential area 1.3 0.6
    - Others 6.4 2.7
    - Total 233.9 100
     
G3 POPULATION IN THE CATCHMENT AREA
     
    Population Population density [km-2] Major cities (population)
    Total 354 1.5 None
     
 

H. LAKE UTILIZATION (3, 10)

H1 LAKE UTILIZATION
    Source of water, recreation (sight-seeing, swimming, sport-fishing).
 

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS (4)

I1 ENHANCED SILTATION
  • Extent of damage: None.
I2 TOXIC CONTAMINATION
  • Present status: Not detected.
I3 EUTROPHICATION
  • Nuisance caused by eutrophication: None.
I4 ACIDIFICATION
  • Extent of damage: None.
 

J. WASTEWATER TREATMENTS (1)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA
    b) No sources of significant pollution.
J3 SANITARY FACILITIES AND SEWERAGE
  • Municipal wastewater treatment systems: None.
  • Industrial wastewater treatment systems

    • No.of industrial wastewater treatment systems: None.
 

N. SOURCES OF DATA

  1. Maitland, P. S. (1981) Introduction and catchment analysis. The Ecology of Scotland's Largest Lochs, Lomond, Awe, Ness, Morar and Shiel (ed. Maitland, P. S.), pp. 1-27. Dr. W. Junk Publishers, The Hague.
  2. Smith, I. R., Lyle, A. A. & Rosie, A. J. (1981) Comparative physical limnology. Ibid., pp. 29-65.
  3. Muller, M. J. (1982) Selected Climatic Data for a Global Set of Standard Stations for Vegetation Science. 306 pp. Dr. W. Junk Publishers, The Hague.
  4. Bailley-Watts, A. E. & Duncan, P. (1981) Chemical characterisation: a one-year comparative study. The Ecology of Scotland's Largest Lochs, Lomond, Awe, Ness, Morar and Shiel (see above), pp. 67-89.
  5. Ibid. (1981) The phytoplankton. Ibid., pp. 91-118.
  6. Ibid. (1981) A review of macrophyte studies. Ibid., pp. 119-134.
  7. Maitland, P. S., Smith, B. D. & Dennis, G. M. (1981) The crustacean zooplankton. Ibid., pp. 135-154.
  8. Smith, B. D., Maitland, P. S., Young, M. R. & Carr, M. J. (1981) The littoral zoobenthos. Ibid., pp. 155-203.
  9. Maitland, P. S., Smith, B. D. & Adair, S. M. (1981) The fish and fisheries. Ibid., pp. 223-251.
  10. The editor's observation.