"The Outer Hebrides represents the western extreme of oligotrophic to mesotrophic standing waters in the UK, and is part of the vast flow-ground on Lewis. Lewis Peatlands contrasts with many of the other UK sites with this habitat type as it comprises an undulating terrain subject to oceanic influences, which is not located within a mountainous landscape. It supports high-quality freshwater loch habitats. The site includes lochs within watershed flows, characteristic of the northern part of Lewis, and lochs within a more dissected terrain in the south of the site. The peatlands and bog systems within the site support nutrient-poor lochs and lochans that contain vegetation typical of the oligotrophic conditions.
Lewis Peatlands is a complex landscape of broad plateaux, valleys, hollows and gentle slopes that supports extensive blanket bogs and moorland where dystrophic water systems occur. The dystrophic waters vary in shape in size but are generally small pools and lochans that can have a complex, interconnected form. The waterbodies are typical of this habitat type being highly acidic, very poor in nutrients and supporting abundant bog-mosses."
Site Details, Special Areas of Conservation (SAC), Joint Nature Conservation Committee