Riverfly Monitoring is our flagship citizen science project. Our volunteer monitors sample river bugs at agreed locations around the River Aire catchment to assess the effects of pollution on life in the river.
Riverfly populations are one of the key indicators of long-term river health problems, as the insects living in the river fall quickly if pollution is present and take a long time to recover after a pollution event.
In 2025, with the support of LNER and Yorkshire Water who funded the project, we set out to expand our The Riverfly Partnership sampling network across North Leeds. To help assess the ecological impact of the pollution recorded by our volunteers as part of the 2025 Outfall Safari - Leeds - Aire Rivers Trust
Read on to find out more about the project and what we found.
The project saw fifteen new Riverfly monitors sample seventeen new Riverfly sites between Horsforth and Roundhay, across four stream catchments. The volunteers came from a range of local environmental groups who, working with some of 'our own' volunteers, partnered with us to enable collection of samples over nine months, across:
The video to the right provides a summary of our work with LNER and our partner organisations as part of the project.
A small tributary of Wyke Beck, colloquially known as Asket Hill Beck off Wetherby Road, Oakwood. Recorded the lowest invertebrate numbers and the least range of indicator groups, with a mean RMI score of 2.17. It also recorded the lowest number of indicator invertebrate groups, with only 3 of the 8 groups present across the survey period. No cause for this issue has yet been identified, and further investigation is required.
A second small tributary of Wyke Beck, Fox Wood Beck in Roundhay Park, recorded the second-lowest average RMI score in the project area at 3.5. A visible pollution source flowing from a culverted watercourse containing two Combined Sewer Overflows and suspected misconnected private pipes is the clear cause of the problem. Investigative action by the appropriate authorities and corrective works are needed to resolve the issue.
Across the wider Wyke Beck catchment, sample counts were consistently lower than average, with a mean RMI score of 5.13, below the Aire catchment mean of 7.65. This suggests that the numerous pollution sources identified along this watercourse during the North Leeds Outfall Safari are having a suppressive effect on the catchment’s ecology.
Gledhow Beck also returned below-average RMI scores for the Aire catchment, with mean values between 4.17 and 5.00. There was a noticeable absence of species intolerant of low water quality. Mayfly (Ephemeridae spp.), flat-bodied stone clingers (Heptageniidae spp.), and stonefly (Plecoptera spp.) were missing from 80% of the sampled sites.
Sampling across the Meanwood Beck and Carlton Beck catchments returned average RMI scores slightly above the Aire catchment mean, at 8.2 and 8.31 respectively. These becks also recorded all eight invertebrate indicator groups across their catchments. This indicates that these watercourses are relatively healthy but could improve further if known pollution sources, habitat structure issues, and erosion problems were addressed.
This project is now complete, but if you want to get involved with citizen science work in Leeds please visit our Citizen Science Page to see what projects we currently have running in your local area: Citizen Science - Aire Rivers Trust
Or contact your local friends of group on to see what projects they are carrying out near you:
Or you can find your local river action group on our interactive map here Friends of the River - Aire Rivers Trust
