Riverfly Census

What is the Riverfly Census?

What is the Riverfly Census campaign?

The riverfly census is all about understanding and improving water quality in UK rivers.

Across several iconic rivers, we use professional sampling to analyse invertebrate life and thereby understand the health of the river and the issues which need tackling. Like all our campaigns, we use professional, scientific evidence to campaign for improved protection of our wild waters.

How does the campaign affect salmon & trout?

Insects are the foundation of the food-chain, with birds and wild fish, such as salmon and trout, depending on them for survival. Not only this, but they are incredibly susceptible to certain chemicals or excesses in the water, making them an excellent indicator of the wider issues in the river. Invertebrate health, numbers and diversity are therefore excellent indicators of water quality; with healthy bugs indicating a healthy water ecosystem.

However, anecdotal evidence, other studies, and our own research has told us for some time that these bugs are in decline. If true, this decline directly threatens the health of our wild fish populations, and at a wider level means our waters could be in trouble.

So in 2015 we set out to confirm this, to understand why invertebrate life on our rivers is in decline, and to learn more about what could be done; and the Riverfly Census was born.

Now in its third year, the census has shown us that invertebrates are under enormous stress from phosphorus and sediment, among other culprits. If not addressed, river health will deteriorate, and we risk losing our most iconic rivers and the life they support. This is a serious issue that needs investment, research and most importantly, action. 

What is our strategy?

The way we operate all our campaigns is consistent across S&TC.

1 - We immerse ourselves in science, doing everything we can to understand the issues and collect relevant, professional, independent data.

2 - Once we have this evidence, we follow the facts and build strategic campaigns which fight for appropriate change.

In regards to our Riverfly Census campaign, we are now at step 2: sorting through the data, understanding the issues, and presenting it to the relevant parties to campaign for better protection of our watery places.

We are currently producing individual reports for the rivers, and tackling their unique issues at a grass roots level with the relevant organisations.

The next step will then be taking our findings national, generating an overarching national policy paper which highlights consistent problems. We aim to tackle things like the Water Framework Directive, EA regulation of farming practices, sewage treatment outputs, ineffective national monitoring, and inadequate discharge guidelines, to name but a few.

How can you help?

With your support, we can continue to understand and fight for local rivers before it is too late.

The Riverfly Census is an important and unique campaign, which no other charity or organisation is undertaking. While many organisations opt for river restorations projects (which only deal with symptoms of water problems), we are trying to tackle the root causes and get to the bottom of what is happening. Our sampling and analysis is done at a scientifically professional level, and the scale of this project is enormous.

We do not receive any government money, and a project of this size needs extensive funding.

Please consider donating or joining us as a member, which will enable us to protect these iconic waterways, and the wild fish and creatures that live there, for generations to come.

What else can you do to support us?

We need to educate people that despite the surface level beauty of local rivers, the water ecosystem itself may be in decline. There are invisible threats under the surface, threats that need tackling NOW.

Therefore we need your help in spreading the word about the Riverfly Census with locals, anglers, nature and water enthusiasts, wildlife lovers, relevant NGO’s and charities, and anyone else who may be interested or able to assist us.

Please see if we are sampling or campaigning for a river near you, and get involved with  by downloading the info packs below and sharing our efforts on social media.

How do we sample?

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.

FACT: 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.

Which rivers have we sampled?








Eastern Cleddau








What have we 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, so keep an eye on the river content below, or sign up for our emails to stay informed.

What difference does the Riverfly Census make?

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.

Educating on hidden issues

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!

How can you get involved?

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.

Please help us to continue the fight for our wild waters and the fish that live there.


£50 funds a sampling net

£70 funds sampling at one site

£200 analyses a sample to species level and biometrically fingerprinted

£400 funds sampling at all sites on a river - providing enough data for 6 months


We gratefully welcome private funding offers from local landowners or those with river access who wish to help us protect their stretch of water. Please donate below or contact our fundraising manager Guy@salmon-trout for an informal discussion on supporting our efforts.

Latest Riverfly Census News

River Itchen damage below Alresford Salads: Autumn 2018 photos

New photos show damage in River Itchen below Bakkavor’s Alresford Salads factory. At S&TC we have long been campaigning to stop Bakkavor discharging their salad wash effluent into the headwaters of the River Itchen. The Itchen is a designated Special Area of Conservation (SAC), and we fear that the chemicals in their discharge are harming […] Read More

Agricultural Bill: Is a ‘Green Brexit’ possible?

The first major Agriculture Bill for over 70 years has now been published, promising a cleaner, greener and healthier environment post Brexit Currently farmers receive €4 billion in subsides each year, which is divided up related to the total amount of land farmed. For current subsidies farmers do not need to ‘do’ anything. The new […] Read More

River Itchen pollution: Alresford Salads trial chlorine-free cleaning products

Is the end of chlorine-based cleaning products at Alresford salad washing plant finally in sight? Finally, it appears Alresford salad washing plant is planning to stop using chlorine-based cleaning products. This would mean that there would no longer be any products used to wash the site’s equipment that could react to form chloramines, which are […] Read More

High resolution monitoring is essential for river conservation

This is a re-posting of an original article from Environmental Technology   High Resolution Monitoring on the Itchen Working on behalf of Salmon & Trout Conservation (S&TC), researchers from the University of Portsmouth have been investigating nutrient concentrations in the Upper River Itchen, in Hampshire, UK, to better understand where phosphorus is coming from and […] Read More

Dwindling flylife evidences a worrying decline of the River Test

Decline of the River Test The River Test is one of our most famous, if not the most famous, trout river in the country; yet we have significant evidence that it is sadly in decline. Furthermore, we can now point the finger firmly in the direction of  Chilbolton and Fullerton Waste Water Sewage Works; or, […] Read More

River Avon: Riverfly Census Results

River Avon Riverfly Census The results are in from our ground-breaking Riverfly Census campaign for the River Avon. View the results below and read more about what we found, why it is important, and what we are doing next! view our Fact Sheet Read our Report view our Data pack What is the River Avon […] Read More

S&TC Cymru: Snapshot survey of the River Tywi (Towy)

  S&TC Cymru has reacted to growing concerns surrounding the prolific algal growth witnessed on the Tywi over recent weeks by conducting a snapshot survey of the most affected part of the river. Conditions at the time of the visit (11th of June 2018) reflected a prolonged absence of rain coupled with long days of […] Read More

Riverfly Census: Whitewater Sampling

Whitewater River Although 2017 was the last year for the 12 Riverfly Census core rivers, we continue to work our way through the rivers added later on (as well as assess and write up the data so far). One such river (Whitewater, a tributary of the Blackwater River) recently led us to work closely with […] Read More

Riverfly Census continues in Wales

The Riverfly Census in Wales Through our S&TC Riverfly Census, a three-year survey using species-level invertebrate analysis, we are currently analysing results from the 12 rivers that kicked the survey off in 2015. We continue to unlock the power of water insects and diagnose the health of rivers nationally- and this is not just limited […] Read More

Welsh charities join forces for World Fish Migration Day

  World Fish Migration Day This Saturday we will be helping to celebrate the third World Fish Migration day. There will be a number of fascinating events and activities in Wales for people to enjoy and learn more about the life-cycle of migratory fish species. This global initiative aims to highlight the importance of conserving […] Read More

documents archive

Stay up to date with our latest news & press releases