The Big River Watch returns as public concern over river health reaches new heights
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 24-30 April 2026.
Since it was launched by The Rivers Trust in 2023, more than 22,000 people have taken part in the Big River Watch with almost 40 per cent being new to citizen science.
Big River Watch citizen scientists gather valuable data that helps The Rivers Trust Movement take vital action to improve rivers.
Big River Watch users have identified more than 30 previously unrecorded river barriers in England, which can significantly impact the migratory journeys of iconic species such as Atlantic salmon, twaite shad, and European eel.
Participants can view live data captured during the week-long campaign via the Big River Watch Data Dashboard
As concern grows over the state of waterways across the UK and Ireland, thousands of citizen scientists are gearing up for the Big River Watch to help monitor the challenges impacting river health that The Rivers Trust is working to address.
Running from 24 – 30th April 2026, The Rivers Trust initiative invites the public to spend just 15 minutes by a river or stream, recording observations of pollution, wildlife, and river conditions through the free Big River Watch app. Survey results are published in near-real time on the Big River Watch online dashboard.
The Big River Watch - the UK and Ireland’s largest mass-participation survey of river health - is already delivering real-world impact. Contributors have identified more than 30 previously unrecorded barriers to fish migration in England, helping to highlight obstacles affecting endangered species including Atlantic salmon, European eel, and twaite shad. Data gathered during each Big River Watch helps fill critical gaps in environmental monitoring – particularly in smaller rivers, streams, and headwaters where pollution often begins but oversight is limited. Once verified, this can be logged on national databases, enabling positive action such as barrier removal or fish-pass installation.
The Big River Watch requires no experience or training in citizen science. Anyone can take part by downloading the free Big River Watch app and spending 15 minutes by their local river or stream to monitor signs of pollution, wildlife sightings, and observations on flow levels. Participants can engage with the Big River Watch as many times as they like in different locations to help improve our understanding of river health.
Michelle Walker, Technical Director at The Rivers Trust, said: “The Big River Watch helps to fill the gaps in environmental monitoring, providing a much 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.”
Emma Brisdion, Communications & Campaigns Manager at The Rivers Trust, said: “This year, the Big River Watch is coming at a time of increased public awareness surrounding the health of our rivers. Water pollution hit the headlines following the unveiling of the Fountain of Filth on London’s Southbank to coincide with Channel 4’s Dirty Business. It’s a conversation we have been a leading voice in for 20 years now, and the Big River Watch is just one of the ways in which we involve the public by providing them with the means to report on the health of the rivers and waterways in their communities. We’re really excited that this year the free Big River Watch app will feature an Irish language translation, sitting alongside existing options for Welsh and English, marking our commitment to widening accessibility, helping us reach even more river loving communities.”
For further information, please see here: The Big River Watch | The Rivers Trust