Getting Started with your own River Group?
A. Ecological and chemical status of your river (Environment Agency)
To see the Environment Agency’s official assessment of your river's water quality and ecological health (including chemicals, phytobenthos, invertebrates, phosphate, etc.):
https://engageenvironmentagency.uk.engagementhq.com/data-publications-water
B. Historic storm overflow spill data (Environment Agency EDM)To see how often storm overflows have spilled in your area:
https://environmentagency.blog.gov.uk/2025/03/27/what-are-the-2024-edm-annual-returns/
C. Near‑real‑time CSO activity on your river
For live or near‑real‑time information on when local combined sewer overflows (CSOs) are discharging, there’s an independent site that aggregates water company alerts:
D. Wessex Water assets (treatment works and other infrastructure)
For an overview of Wessex Water’s sewage treatment works locations:
River testing.
There are three main kinds of testing.
1) Riverfly testing (to count invertebrates living in the river). The Riverfly Partnership offers training. This is good for public engagement. People enjoy doing it - getting into the river and collecting specimens. It will also, almost certainly, give you evidence and encouragement that the river is 'alive'. But you will need to build a database of results over a couple of years before you can use it to identify potential pollution incidents.
2) Bacteriological testing (E. coli). We recommend using Petrifilm for ease and low cost. For 5 sites tested weekly for a year using Petrifilm, budget roughly £500 per year for the plates, about £400 for a 'good-enough' incubator, and perhaps £100 for pipettes and other consumables. (£1,000 total).
3) Chemical testing. To test ammonia, phosphate and nitrate at 5 sites once a week for a year with Hanna egg (Checker) meters, budget roughly £300 one‑off for the three meters, and about £800 per year for reagents, plus a small amount (£50) for containers and bits – so around £1,200 in the first year, then £800–£1,000 per year after that assuming you keep the same sampling intensity.
Bacteriological testing will get you immediate evidence of faecal pollution (from sewage spills, leaking drains, field run-off (slurry), overflowing slurry lagoons, septic tanks, livestock and birds). If you find a problem, then you have to move on and identify the source.
Chemical testing will give you wider evidence of (mainly) agricultural pollution - from fertiliser and spread-slurry run-off.
Riverfly testing will give you evidence of river health (or its lack).
Where you start probably depends on what you find beforehand in terms of ecological health and spills data - and what you decide you want to tackle first.
For more information, do contact us.
To see the Environment Agency’s official assessment of your river's water quality and ecological health (including chemicals, phytobenthos, invertebrates, phosphate, etc.):
- Go to the Environment Agency’s Catchment Data Explorer:
https://environment.data.gov.uk/catchment-planning/ - In the search box, type the name of your river and press enter.
- In the results, click on the relevant River water body for your stretch.
- On the water body page:
- Look at the Classification section for the latest overall, ecological and chemical status.
- Scroll down to see the detailed element breakdown – this is where you find things like phytobenthos, macroinvertebrates, phosphate, fish, and other components that make up the status.
- From that same page you can also click through to Monitoring locations and then out to the Water Quality Archive / Water Quality Explorer to download the underlying sample data for specific determinands (e.g. phosphorus, ammonia, biological metrics) for that stretch of river.
https://engageenvironmentagency.uk.engagementhq.com/data-publications-water
B. Historic storm overflow spill data (Environment Agency EDM)To see how often storm overflows have spilled in your area:
- Go to the Environment Agency’s Event Duration Monitoring (EDM) Annual Returns page (this covers storm overflows across England):
https://www.data.gov.uk/dataset/19f6064d-7356-466f-844e-d20ea10ae9fd/event-duration-monitoring-storm-overflows-annual-returns - From there you can either:
- Follow the link to the Storm Overflow map/portal and zoom in to your area, then click individual overflow points to see how many times and for how long they spilled in the most recent year; or
- Download the relevant annual data file (e.g. 2024) and filter it for Wessex Water and for postcodes/locations near you.
https://environmentagency.blog.gov.uk/2025/03/27/what-are-the-2024-edm-annual-returns/
C. Near‑real‑time CSO activity on your river
For live or near‑real‑time information on when local combined sewer overflows (CSOs) are discharging, there’s an independent site that aggregates water company alerts:
- Flood Mapper
- https://www.flood-mapper.com/data-explorer
D. Wessex Water assets (treatment works and other infrastructure)
For an overview of Wessex Water’s sewage treatment works locations:
- Wessex Water Sewage Treatment Works Map (third‑party)
https://www.southwest-environmental.co.uk/further%20info/in%20depth/wessex_water_sewage_treatment_works_location_maps.html
River testing.
There are three main kinds of testing.
1) Riverfly testing (to count invertebrates living in the river). The Riverfly Partnership offers training. This is good for public engagement. People enjoy doing it - getting into the river and collecting specimens. It will also, almost certainly, give you evidence and encouragement that the river is 'alive'. But you will need to build a database of results over a couple of years before you can use it to identify potential pollution incidents.
2) Bacteriological testing (E. coli). We recommend using Petrifilm for ease and low cost. For 5 sites tested weekly for a year using Petrifilm, budget roughly £500 per year for the plates, about £400 for a 'good-enough' incubator, and perhaps £100 for pipettes and other consumables. (£1,000 total).
3) Chemical testing. To test ammonia, phosphate and nitrate at 5 sites once a week for a year with Hanna egg (Checker) meters, budget roughly £300 one‑off for the three meters, and about £800 per year for reagents, plus a small amount (£50) for containers and bits – so around £1,200 in the first year, then £800–£1,000 per year after that assuming you keep the same sampling intensity.
Bacteriological testing will get you immediate evidence of faecal pollution (from sewage spills, leaking drains, field run-off (slurry), overflowing slurry lagoons, septic tanks, livestock and birds). If you find a problem, then you have to move on and identify the source.
Chemical testing will give you wider evidence of (mainly) agricultural pollution - from fertiliser and spread-slurry run-off.
Riverfly testing will give you evidence of river health (or its lack).
Where you start probably depends on what you find beforehand in terms of ecological health and spills data - and what you decide you want to tackle first.
For more information, do contact us.
