The ECN Data Centre

Site Information: Llyn Llagi

Sponsoring organisation(s)

Department for Environment, Food and Rural Affairs (through United Kingdom Upland Waters Monitoring Network)

Network(s) this site belongs to
UK Environmental Change Network
Upland Waters Monitoring Network

Site characteristics

Altitude m

The catchment area is indicated with a black line.
Click map to enlarge.

Area of Lake ha
Mean annual pH* 5.5
Mean annual water temperature* 9.2
* calculated from the ECN Data Centre database
Information held about this site
View a list of datasets collected at this site
View a list of publications about this site


Llyn Llagi occupies a north-facing corrie in the central area of the Snowdonia region of North Wales. The lake lies at 380 m beneath a steep backwall and comprises a deep, almost circular basin (maximum depth 16.5 m) bordered by an extensive shallow (1 m deep) rim. The lake covers an area of 5.67ha and the primary inflow constitutes the outflow stream from Llyn yr Adar. The lake drains to the north-west to the Nanmor valley. The catchment (157 ha) consists primarily of Ordivician slates and shales of the Glanarfon series. The backwall is composed of a large doleritic intrusion with small intrusions of fine microgranites and volcanic tuff. The catchment soils are mainly stagnopodsols and gleys, interspersed with blanket peats. The vegetation is characterised by Calluna (heather), Molinia (purple moor-grass) and Eriophorum (cotton grass), and the catchment is grazed at a low intensity by sheep. The lake and much of the catchment lie within a designated Site of Special Scientific Interest (SSSI).

Llyn Llagi is classified as having high acid deposition.

Ewan Shilland


Related links



Mr Ewan Shilland

Environmental Change Research Centre, Department of Geography, University College London, Pearson Building, Gower Street, London, WC1E 6BT

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