The Big River Watch calls on public support to help monitor river health following summer of record dry conditions
People across the UK and Ireland urged to become citizen scientists and gather data on river health as part of the Big River Watch from 18th – 24th September 2026.
11/09/26
As a summer of record-breaking dry weather and prolonged heat begins to come to a close, thousands of citizen scientists are preparing to take part in the Big River Watch to help monitor the impacts of extreme weather and pollution on river health and inform vital conservation work by The Rivers Trust.
From 18th – 24th September 2026, the public are invited to record observations of pollution, wildlife, and river conditions through The Rivers Trust's free Big River Watch app. Surveys take just 15 minutes to complete and key results are published in near-real time on the Big River Watch online dashboard, allowing anyone to see and help build a national picture of river health across one week.
Being the UK and Ireland's largest mass-participation river health survey, the Big River Watch returns at a crucial time following a summer of climate-change induced weather extremes which have caused significant stress for rivers and waterways. As much of the UK and Ireland begins to see rain return, the risk of 'weather whiplash' could increase pollutants entering waterways through soil runoff, or it may trigger significant flooding across the landscape, further exacerbating the poor state of rivers, endangering wildlife and causing anguish for communities. Now more than ever, The Rivers Trusts needs the public's help to fully understand the impact this is having on our waterways.
Alison Matthews, Chalk Stream Programme Manager at The Rivers Trust said: “This September’s Big River Watch follows an exceptionally hot and dry summer, and many of our river catchments will have been under significant stress. Now there has been some relief from those conditions, this survey is an opportunity for citizen scientists to help us understand if the rivers are starting to show signs of recovery or if they are still showing signs of distress. Participants may still see low water levels and algae, but recent rain could also bring further challenges by introducing run off containing pollutants and sediment that make rivers look murkier and cause further problems for river wildlife. But we don’t want participants feeling too down if they do spot these things, it's important that we know what issues our rivers are experiencing so that we can support the best actions possible to restore them. The survey is also a great way for people to appreciate the nature around them; we need people to fall in love with their rivers so that they can help protect them for future generations.”
As well as identifying river conditions, Big River Watch participants provide valuable data on pollution hotspots, wildlife sightings, and locations of man-made river modifications – all key indicators of river health. Contributors have already helped deliver real-world impact, identifying a potential 100 previously unrecorded river barriers to fish migration in England alone, helping to highlight obstacles affecting endangered and iconic species such as Atlantic Salmon, European eel, and twaite shad. Once verified, these barriers can be logged on the national River Obstacles database, enabling river restoration actions to take place, such as barrier removal or the installation of fish or eel passes.
Thousands of people from different backgrounds and communities have been inspired to become first-time citizen scientists through the Big River Watch. No training or experience is required to take part, making it an accessible introduction to citizen science and encouraging engagement with environmental issues. Participants need to spend just 15 minutes by their local river or stream to record their observations and are encouraged to take as many surveys as they like in different locations to help build a much broader picture that fills the gaps in current environmental monitoring. The survey is available in English, Welsh and Irish, and the app contains handy pollution and wildlife ID guides.
Michelle Walker, Technical Director at The Rivers Trust, said: “The Big River Watch helps to fill the gaps in environmental monitoring, providing a much-needed broader picture of river health across the UK and Ireland. Citizen science has proved to be an important tool in monitoring our rivers, and this year, I’d like to see Big River Watchers celebrating and surveying the smaller rivers, streams and tributaries. It’s often the headwaters and smaller streams that provide vital information about what’s going on in our catchments. Most pollutants will eventually reach the larger rivers downstream, but by surveying the headwaters, we can more easily identify the initial sources of pollution and stand a better chance of tackling issues. Other citizen science initiatives, such as riverfly monitoring, focus on these upper reaches too, and more Big River Watch surveys in headwaters would allow us to pair up these datasets more reliably, and gain deeper insights.”