The ECN Data Centre

Site Information: Loch Leven

Sponsoring organisation(s)

Natural Environment Research Council (through UK Centre for Ecology and Hydrology)

Network(s) this site belongs to
UK Environmental Change Network
UK Lake Ecological Observatory Network

Site characteristics

Altitude m

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

Area of Lake 1330ha
Mean annual pH* 8.3
Mean annual water temperature* 10.5
* 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


Loch Leven is the largest, shallow, relatively nutrient-rich, lowland loch in Scotland. It is situated about 35km north of Edinburgh at an altitude of 107m. It has a surface area of 13.3km2 and has a mean depth of 3.9m. The Loch Leven catchment covers 145 km2, consisting mainly of arable crops (38.6%) and improved pasture (31.5%), but also upland moor (11.6%), coniferous woodland (3.8%), heathland (3.5%), rough grazing (3.5%), suburban/rural development (2.2%) and the rest - deciduous woodland, bog, bare ground, inland water - (5.3%). The highest part of the catchment is at 497m.

Loch Leven is particularly renowned for its large numbers of migratory, breeding and overwintering waterfowl and its world famous brown trout fishery. It is a Site for Special Scientific Interest (SSSI), a National Nature Reserve (NNR), a Special Protected Area (SPA) and a Ramsar site. Loch Leven is also a water supply source for downstream paper mills and textile factories. Although the overall quality of the site is good, the loch has suffered from periodic cyanobacterial (‘blue-green algal’) blooms for many years. These have occurred, largely, as a result of substantial amounts of phosphorus entering the loch, combined with a relatively low flushing rate and a favourable light-climate. The blooms have a direct impact on the various users of the loch, on the local economy, and occasionally pose a potential risk to human health. In terms of conservation interest, algal blooms also reduce light penetration into the water, reducing macrophyte (aquatic plant) growth, with associated impacts on macroinvertebrate, fish and the significant bird communities.

The Centre for Ecology and Hydrology (CEH) and its various predecessor bodies have been monitoring the lake since the mid 1960’s and have built up long-term data sets of various biological and chemical parameters. As a result, Loch Leven has become an invaluable research resource for addressing issues such as eutrophication and climate change. Since the 1970s, Scottish Natural Heritage (SNH), Scottish Environment Protection Agency (SEPA) and other agencies have been involved in an action programme to improve the ecology and water quality of Loch Leven. This has been aimed primarily at reducing the intensity and frequency of phytoplankton blooms occurring, and enhancing water clarity, by reducing the loadings of phosphorus into the loch. The programme has been successful in reducing the phosphorus load from point sources and the Loch Leven Catchment Management Plan has been addressing the problem of diffuse sources of nutrients.

Current research is focussed primarily on whether Loch Leven is showing signs of ecological recovery from eutrophication pressures following reductions in external loadings of phosphorus, the main limiting nutrient. Recent evidence suggests that although there have been encouraging signs of improvement in the ecology of the loch, a sustained recovery has yet to occur. To reduce the year-to-year variability of water quality and further the ecological recovery of Loch Leven, more research into lake and catchment management is being undertaken. CEH Edinburgh are currently investigating the impacts that various pressures such as internal loading of phosphorus, climate change trends and fisheries management are having on water quality as well as re-evaluating the Loch Leven catchment nutrient budget. Loch Leven is also a key study lake in the Euro-limpacs EU Framework 6 project, part of which aims to unravel the combined effects of climate change and nutrient enrichment on ecological response in European lakes.

© Centre for Ecology and Hydrology


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Dr Linda May

UK Centre for Ecology and Hydrology
Bush Estate, Penicuik, Edinburgh, Midlothian, EH26 0QB

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