New research from the Environment Agency shows steps already being taken to reduce pollution in Windermere will help protect the lake’s water quality from algae growth, even as the climate changes.
Nevertheless, more ambitious action is needed to fully offset predicted impacts.
Scientists have studied Windermere for decades, with each piece of research adding another part to the jigsaw. Today’s report is part of a wider programme of work to understand the pressures the lake faces and guide action in response.
The study looks at nutrients. Substances like phosphorus and nitrogen that enter lakes from wastewater and from land. In small quantities these are a natural part of lake life, but in higher concentrations they can cause serious problems.
The research, carried out by the Environment Agency’s Chief Scientist’s Group, in collaboration with the UK Centre for Ecology & Hydrology (UKCEH), uses computer modelling to understand how climate change could change the amount and timing of nutrients reaching Windermere and Esthwaite Water, a small lake draining into Windermere, over the coming decades and what different types of action could do to help.
The findings show that by the 2070s, with climate change, the amount of these pollutants entering the lakes each year could increase by up to 7%. The rise would be most pronounced in summer, precisely when the lakes are busiest with swimmers, visitors, and local communities.
If nothing is done, this would make harmful blue-green algae more likely. Blue-green algae can make water unsafe to swim in, harm wildlife, and damage tourism and recreation.
However, the research also shows that action works. Scientists tested three approaches to reducing the pollution entering the lakes, including upgrades already underway to how wastewater is treated and the positive impact land managers and farmers can have to reduce nutrient run off in erosion of soils and safe storage of manures.
All three approaches reduced the number of days when blue-green algae reached levels the World Health Organisation considers a risk to human health, even when the additional pressures of climate change were factored in.
In Windermere, the most ambitious option tested – removing all wastewater including septic tanks – was enough to fully cancel out the projected effects of climate change on the lake in the next 50 years.
Andy Brown, Environment Agency Water Regulation Manager said
Windermere is one of England’s most treasured lakes and we are absolutely committed to protecting and improving its water quality.
This research builds our understanding further and gives us and our partners a stronger scientific foundation for making the right decisions about where investment needs to go, how we regulate pollution, and how we plan ahead for the pressures that climate change will bring.
The science is clear that local action can make a real difference. Reducing pollution from both wastewater and farming can help protect this lake for future generations, and that is exactly what we are working to achieve through our partnerships with Love Windermere, Only Rainwater into Windermere, and the wider community.
The research also makes clear that there is no single solution that works for every lake and that protecting water quality in future will require a coordinated effort across multiple sectors. Action already being taken will help, more ambitious action, that is currently being scoped, is needed to fully offset impacts.
Esthwaite Water, which is smaller and shallower than Windermere, remained a concern under every future scenario the scientists tested.
This is because factors like a lake’s size, depth and historic activities, all affect how it responds to pollution and climate change. Managing these pressures well means that understanding each lake on its own terms is essential.
The Environment Agency will use the evidence from the Nutrient Futures for Windermere report to push for more ambitious water company improvements in future regulatory cycles. The modelling approach is also transferable and could be applied to other lakes across England facing similar challenges.
The full report is available at Nutrient futures for Windermere – GOV.UK