The big water quality issue in our rivers and why it matters - Riskaware

The big water quality issue in our rivers and why it matters

The Environment Agency revealed in 2020 that only 14% of English rivers are of good ecological standard.

Looking back just four years, figures from the Environment Agency show that 97% of rivers were judged to have good chemical status. Now, chemical levels of phosphate and nitrates are a common concern. Similarly, there has been no improvement to the ecological health figures of 2016 where only 16% of waterways were considered to be in good health.

Undeniably, English rivers have experienced a dramatic decline in health. Although the UK Government have set targets for 100% of rivers to be classed ‘good’ by 2027, these stats indicate that this goal is at risk of not being achieved.

The reason for a decline in river health

This trend is happening for many reasons, from man-made issues to changing weather conditions. Two primary examples are sewage overflow and pollutant run-off.

Combined Sewage Overflow (CSO)

CSOs are designed to collect rainwater runoff, for example during a storm, as well as domestic and industrial sewage waste. In normal conditions, all excess water and sewage would be transported to a treatment plant. However, when these pipes already contain large amounts of rainwater due to extreme weather conditions and then sewage also overflows, the content must be diverted elsewhere. This often results in raw sewage being pumped into rivers. Due to changes in weather patterns, this is happening much more often than it did in the past.


Nitrate and phosphate levels occur naturally in rivers and are fundamental to their overall health. However, when the level of these chemicals become too high, excessive algae blooms can occur which have the potential to kill fish and other wildlife in the river habitat.

High concentrations of phosphates and nitrates can be due to several factors. Often pollution from poor land management – including agriculture practices, fertiliser, and cattle waste – will run off directly into rivers. Similarly, people can dispose of waste improperly into drains which may deposit straight into river water without being treated.

On the whole, the European Environment Agency shows that phosphate and nitrate concentrations in freshwater bodies has been steadily declining, but that groundwater levels are still a concern.

Fish health

Migratory fish populations have dropped by 76% in the last 50 years. English rivers are relatively sparse when it comes to fish and other marine life. This can be due to both polluted waters affecting their health and obstacles preventing their migratory and reproductive cycles. For example, weirs and dams block fish from swimming upstream to spawn. Fish are an integral part of various ecosystems and so this decline could have many detrimental knock-on impacts.

What are the impacts of poor river water quality?

Lifeless waterways are a prominent possibility. Without fish populating the rivers and supporting the ecosystem, other vegetation and wildlife will also be eradicated. Already fish populations are in decline and many rivers in the Bristol Avon Catchment area are displaying signs of lifelessness. If water quality continues to worsen, this problem will accelerate. Algae blooms can have a similar effect as they pose a threat to the health of surrounding river wildlife.

Humans will inevitably be affected by downstream impacts. Algae blooms can also be potentially dangerous to people and dogs, while raw sewage can be harmful for swimmers and can result in large amounts of remaining waste.

How can we tackle the problem?

Targeted intervention is key. Gathering data about river quality, such as chemical levels, allows people to identify areas that present particularly poor conditions and therefore prioritise these areas for more regular study and positive action.

Building awareness of this issue is also imperative. Getting the public to understand the severity of the problem and what it means for the state of our environments and our populations can help drive more active conservation work and funding.

Bristol Avon WaterBlitz river health results

The Bristol Avon WaterBlitz is a great example of how scientists, the public, environmental organisations, and many more, can work together to achieve positive change for the health of rivers. Their aim is to conserve and enhance the status of the area’s water bodies, through education, consultancy, community engagement, and practical restoration.

In 2020, 313 Citizen Scientists took part in the Bristol Avon WaterBlitz organised by Bristol Avon Rivers Trust (BART) in association with FreshWater Watch. Gathering samples from 268locations in the catchment area, the event provided extensive data on the condition of Bristol Avon rivers, such as phosphate and nitrate levels, water colour, litter and other qualitative factors.

Results showed that 51% of samples indicated high nitrate levels and 30% showed high phosphate levels, with levels shown to be slightly higher in areas near agricultural sites. These results are displayed on the BART website through a data visualisation platform developed by Riskaware. It maps the data collected by Citizen Scientists onto the water courses in the catchment to allow stakeholders to assess river quality on a holistic scale as well as enabling users to drill down into the detail of each measurement site.

Read more about our work with BART

This information helps BART to identify areas for further sampling and target their further conservation and restoration activities. The platform could be flexibly applied to other areas, allowing for similar targeted intervention to occur for other rivers in the UK and beyond.

More events have been hosted throughout 2021, including a local event at the Land Yeo river in May which resulted in 71 new samples, 67% of which showed high levels of nitrate and 25% of which showed high levels of phosphate.

BART carry out work throughout the year to protect our rivers for the benefit of people and wildlife. They host many volunteer events and so we would encourage you to stay updated with their latest projects and sign up to take part.

To learn more about how Riskaware and BART have worked together read our article.

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