The Lake District is the most visited of the UK’s 15 National Parks, welcoming upwards of 19m visitors each year.  The National Park Authority works within the Lake District National Park Partnership with representatives from the public, private, community and voluntary sectors in a collective commitment to create and maintain a place where a prosperous economy, world class visitor experiences and vibrant communities all come together to sustain the spectacular landscape, its wildlife and cultural heritage. 

In recent years, the UK has seen a sharp rise in the popularity of outdoor swimming which is reflected in increased participation in lake bathing and, in a more organised sense, open water swimming.  The Outdoor Swimming Society acknowledges the work that the Lake District National Park Authority (LDNPA) is doing to actively encourage free swimming.

Tourism operators have been quick to respond.  An area of the LDNPA website dedicated to lake swimming lists six suppliers providing instruction and safety support services. As well as many year-round casual uses, Windermere is home to the Great North Swim, an annual open water swimming event which regularly attracts up to 10,000 swimmers.

The Lake District National Park Partnership’s Plan 2015-20 identifies climate change as one of the key risks facing the Lake District National Park.  This relates in particular to the risk of more frequent and severe flooding, but the increased likelihood of extreme weather events of all kinds is generally acknowledged.  Falling lake levels can be expected in summer and poorer water quality as pollutants become more concentrated.  Erosion caused by heavy rain will increase siltation. Toxic blue-green algae may become more common in lakes affecting recreational use.  Climate Change adaptation is embedded throughout the Partnership Plan.  The evidence-based approach of UK National Parks requires management to be informed by reliable and timely data, reported through 5-yearly State of the Park Reports.

Windermere is the largest and busiest of the Park’s 16 main lakes.  The Windermere Lake Action Plan sets out key actions to secure and improve the lake environment and the community and economic benefits this provides.  Actions include effectively managing lake swimming through better evidence, understanding needs and improving key locations. 

The issue identified is how to ensure that infrastructure, facilities and organisational capacity can accommodate the growing popularity of lake swimming in the Lake District National Park, including in its more organised form of open water swimming events, while taking account of expected seasonal adjustments in lake surface water temperature.

Changes in Lake Surface Water Temperature can influence bathing conditions in a number of ways, including requiring the wearing of wetsuits for safety reasons or the triggering of conditions which favour blue green algae.  In general, especially warm conditions are likely to result in increased casual user activity, offering new business opportunities but also giving rise to safety issues involved with managing increased pressure.

The CDS based Lake Surface Water Temperature (LSWT) application will help to inform seasonal adjustments to operational decisions taken by event managers, businesses and organisations responsible for managing a wide range of lake and lakeside facilities.

The seasonal forecasts will potentially show when there is a risk of deviation from the historic norm.

Systematic monitoring of the monthly release for Windermere will enable operators and managers to anticipate an upturn or downturn in normal usage or to identify potential risk factors that will need careful monitoring as the time is approached. 

"The Climate Data Store has brought together multi-agency seasonal forecasts in a harmonised system, and allows us access to more models than has historically been the case. This means we can take advantage of the collective wisdom of forecasts, and communicate uncertainty to the user efficiently. The ability to offer continually-updating information is of particular interest, as decisions are made by stakeholders all year round. The Lake Surface Water Temperature application may enable organisers of the Great North Swim to anticipate unusual lake conditions over the course of the six months preceding the event, which takes place each June."