Loch Shiel EUR-26

Lat.56.803 Lng.-5.564 Alt.4.5
Riparian Nation(s) UK
Surface Area 20 km2 Mean Depth 40.5 m Volume 0.9 km3
Shoreline 77.6 km Catchment Area 234 km2 Residence Time 1.4 yr
Frozen Period Occasional Mixing Type Monomictic Morphogenesis/Dam Glacial
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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 0.8925 km3.

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).

Photo of Loch Shiel
Photo: A. Kurata