Big Windermere Survey reveals snapshot of winter lake health

  • The results of the February Big Windermere Survey have been released this week, providing a snapshot of winter water quality across the lake and the rivers that feed into it. 
  • 100 citizen scientists took part in the fourth survey this weekend, which will provide a full year of data about Windermere. 
16th February 2023

Scientists from Lancaster University and the Freshwater Biological Association have published the latest results of the largest ever citizen science survey examining the water quality of Windermere – England’s largest natural lake. 

Building on results from the previous two surveys in June and November 2022, this third set of data produced by the Big Windermere Survey project includes results from water samples collected by more than 100 volunteers from 93 locations on 5 February 2023.   

The data have been released just after the fourth seasonal Big Windermere Survey took place this weekend.  

Key findings from the February 2023 data include:

  • Bacteria  

    Low levels of E. coli and intestinal enterococci bacteria, indicators of potential contamination of water by faecal material either from humans or from animals, were found. 100 % of all sites in the survey had levels of these bacteria that would meet standards for Good or Excellent bathing water quality under the European Union Bathing Water Directive.    
  • Phosphorus  

    100 % of river sites had low concentrations of soluble reactive phosphorus, consistent with standards for High status under the European Union Water Framework Directive. Total phosphorus concentrations at 21 % of all lake sites were consistent with standards for High or Good status; 14 % of Windermere shoreline sites were consistent with these same standards.    
  • Nitrogen  

    Nitrate concentrations were low, below 0.95 milligrams of nitrogen per litre in all samples. Total ammonia concentrations were very low with the vast majority of sites being below the limit of detection. 

The Big Windermere Survey aims to provide unparalleled scientific evidence of water quality within the lake and its catchment, helping to identify priority areas where action can be taken to improve the condition of Windermere. 

Dr Louise Lavictoire of the Freshwater Biological Association said: “We’re grateful to the citizen science volunteers who have been out and about collecting samples once more this weekend to establish the state of the lake in Springtime. This will complete the first year of this fantastic, evidence-gathering project and a more detailed report will follow. We’ll be working further with our fantastic volunteers and also the wider community to share the findings and discuss next steps.” 

Jim Radcliffe, Chair of the Love Windermere Partnership, said: “The Big Windermere Survey is a large-scale citizen science project, bringing together people from across the community and giving them an opportunity to actively participate in finding out more about the lake that they care so much about. 

When the full year of data has been analysed later this summer the scientists will be able to draw conclusions about the health of the lake and help us to identify where there may be particular problem areas and prioritise action to tackle them. In the meantime, we are committed to sharing all of our data straight away.”   

The full data set from the first three seasons of the Big Windermere Survey is openly available to the public on Cartographer via the Freshwater Biological Association website at ( The Big Windermere Survey scientists have also produced a briefing note to help understand the findings, available via the same website. 

To date, the project has received generous funding from Lancaster University’s Vice-Chancellor’s Prize for Participatory Research (2021-2022), and from the Environment Agency and United Utilities through the Love Windermere Partnership. The Freshwater Biological Association is a partner in the Love Windermere Partnership and data from the survey directly feeds into decision-making by the partnership. The survey is also supported by the UK Centre for Ecology and Hydrology, Lake District National Park Authority, South Cumbria Rivers Trust, Brathay Trust, National Trust, and other independent experts.