Grass buffer strips on field margins have reduced soil erosion around Loch Leven, contributing to vast improvements in water quality in the past 25 years.

Research by environmental research council NERC, the Centre for Ecology & Hydrology (CEH) and Scottish Natural Heritage (SNH) this week showed that water quality has improved markedly since 1992, when Loch Leven was visibly blighted by poisonous, blue-green algal blooms and murky water. The pollution was estimated to have cost the local community more than £1 million, which led to the formation of a ‘catchment management group’ and plans to clean the Loch.

The improved water quality is mainly the result of less phosphorus and fewer pesticide residues entering the Loch, which has left the water clearer and allowed species of plants and aquatic life to bounce back, researchers said.  

In addition to better land management, there have been improvements in sewage works on the Loch and the local woollen mill has stopped discharging pollutants into the loch. Scottish agencies have identified Loch Leven as a priority for restoration in light of its conservation status (the site is designated SSSI, SPA, Ramsar site & NNR), and in order to meet European Union Water Framework Directive targets.

In recent years, the local management group has had to look again at phosphorous levels, which are on the rise once more.

On Wednesday, Dr Linda May of CEH, who has led the monitoring programme for the last twenty years, said, "The enormous improvement in water quality at Loch Leven over the last 25 years, and the associated improvements in food and habitat for wildlife, provide a world leading example of what can be achieved when scientific evidence is used to underpin restoration and management activities. Lessons learned at Loch Leven are now being used to inform lake restoration projects across the world, especially in developing countries. Our achievements at Loch Leven are frequently described by scientists and lake managers alike as ‘inspirational'."

Wull Dryburgh, Scottish Environmental Protection Agency’s (SEPA) Catchment Co-ordinator, added, “In general, Loch Leven is an example of the cumulative effect of lots of small-scale discharges from a variety of sources – on their own they may seem fairly insignificant, but on a catchment-wide scale they can build up to a big problem. These discharges include run off from agricultural land which SEPA is tackling through diffuse pollution priority catchments and Loch Leven has been chosen for this approach in 2018/19.

“By visiting farmers and land managers and discussing farming practice, our staff can see if there are any areas that need tightening up, such as animal housing, pesticide fill/mix areas and fuel storage. We’ve already had success in a number of areas in Scotland, seeing compliance rates rise from 36% to 84%. An improvement like this could make a real difference to water quality in Loch Leven and build on the good work already done in the catchment by various bodies, farmers and land managers to minimise diffuse pollution impacts.”