Riverfly Census

You may be wondering: how can something as small as an insect have any value in something as vast as a river? The fact is, without water insects, our fish, birds and river mammals will struggle to find enough food.

Unfortunately, numbers of these bugs are lower than ever on a national scale. However, our Riverfly Census campaign is the first step towards understanding the decline and finding solutions!

Water insects are great indicators of water quality. They live for months, sometimes years, below the surface in their nymph stages. Because different insects have different tolerances to pollution, the presence or absence of certain species is a simple but effective way of finding out what pressures a river might be experiencing.

Here’s how we use insect samples to find out what’s going on:

Census Process Image 1

A 3-minute kick sweep sample is taken at a river site making sure to survey all the different habitat types.

Census Process Image 2

The sample is pickled using a special alcohol. This preserves the insects so that counting and identification can be done at a laboratory.

Census Process Image 3

The sample is sorted into groups by an expert and the insects are identified to species level using a microscope.

Census Process Image 4

The list of species present is put into a unique scientific calculator. This gives a value for how much the site is being impacted by four key stressors.

What we've found


The sampling may have stopped, but the fight for healthy waters goes on.

It's all hands on deck for the S&TC Science team who are currently analysing the Riverfly Census results! We are working through the 12 core rivers chosen at the start of the project which have been sampled over the past 3 years. Extracting all the information in this study will take time but we will be publishing results on all rivers soon. Our findings will be revealed a river at a time, keep an eye on the slider below to see when your river is added!


Coming soon!

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Coming soon!

Using the census to make a difference

Join the monitoring revolution

We need people like you to change the way our rivers are managed by demanding better protection and monitoring.

We believe that the 20 Census rivers are only the beginning, and that all UK rivers deserve a proper diagnosis.

We recognise that we cannot achieve this alone, so to spread the success of the Riverfly Census’ species-level methodology, we will soon be launching our SMARTrivers initiative.

S&TC SMARTrivers

S&TC SMARTrivers will enable volunteers, supported by a training scheme, to undertake the essential monitoring necessary to kick start real improvements on their rivers.

This initiative goes beyond the excellent Riverfly Partnership monitoring scheme, as samples are taken away from the riverbank and identified with a microscope.

This higher resolution analysis makes the data directly comparable with existing Environment Agency monitoring data, so it can strengthen the information that already exists, whilst preventing effort duplication.

If a volunteer sample is significantly different (missing species and/or low abundance) from its original benchmark, it can be sent to our approved laboratory for professional supplementary analysis and biometric finger printing.

Agreeing Local Bespoke Targets

Our Census sparked the development of unique insect targets for the rivers Test and Itchen.

Hampshire Environment Agency will now feature these targets in their own monitoring.

We are working to agree simple benchmarking figures like this for all rivers so that we can help local river managers develop solutions.

S&TC SMARTrivers monitors will play an important role in helping us continue this work and establish such targets.


Support smarter monitoring to achieve real results in your river

Fed up of not really knowing the story under the surface? We see a future where all rivers in the UK have intelligent monitoring and an accurate baseline for measuring positive change. The Riverfly Census is a proven methodology to obtain these benchmarks, but we need your support to roll it out further across the UK.