The state of UK rivers has become a matter of great public concern and a hot topic in the media.

A real fear is that pollution is likely to increase as a result of climate change.

In the news we frequently hear about:- 

• Only 14 percent of rivers in England have good ecological status according to Water Framework Directive data
• Untreated sewage is being released into rivers from combined sewer overflows
• Rivers are unsafe for bathers and any recreational use.

You would conclude from this that our rivers are in an absolutely terrible state and that water quality is getting worse. However, according to Dr Daniel Read, a freshwater microbiologist, from the UK Centre for Ecology and Hydrology

the reality is that our rivers are actually in a better state than they have been for some time.

A study, funded by NERC analysing 200,000 macro vertebrates that live in freshwaters from 1989 to 2013, showed patterns of improving diversity and ecosystem health. The reason for this is that water quality as a whole has got better in England and this is largely driven by the introduction of the urban wastewater directive that regulates emissions from waste water treatment works.

It’s true some sections of rivers have got worse even with this general trend of improvement. Furthermore, we can’t assume that things are going to stay the same into the future. Research from the University of Sheffield looked at various climate scenarios and the impact on a group of macro invertebrates. The findings were that climate warming is likely to alter the composition of macro vertebrate communities so that they become more sensitive and vulnerable to chemical pollutants.

The nature of pollutants we see in freshwaters has changed over time and become much more complex. These now include things we use in our households such as soaps, shampoos, disinfectants and other cleaning products; personal care products such cosmetics, insect repellants and suncreams with UV filters; medicines such as antibiotics and anti-inflammatory creams and foods such as sweeteners and microplastics.

Chemicals that we use on animals, in farming and in industry have become much more diverse and are likely to continue to do so.  On a European scale there are real hotspots of threat largely driven by levels of wastewater dilution.

The UK Quality Freshwater Programme, funded by UKRI – the National Council of Environment Research – and Defra, seeks to help us understand better the sources of pollution in river systems and how they are changing, accumulating in our environment and having an impact on our ecosystems.

The results of this research will be used to improve the state of our UK rivers and to inform policies related to agricultural practices and regulations for water companies and waste water organisations. 

PACIFIC – PAthways of Chemicals Into Freshwaters and their ecological ImpaCts – is one of five research projects within the programme each focusing on a different aspect of water quality. It is a four year project which started in 2022 and is a collaboration of UKCEH, University of Bath, University of Oxford and the Environment Agency.

Led by Dr Daniel Read, UK Centre of Ecology & Hydrology, the £1.6m project focuses on  freshwater microbial communities which play a critical role in maintaining the health of freshwater ecosystems and the organisms that live in them. There is a huge range including bacteria, fungi and one of the most visible is green algae which makes water go green. They control the flux of organic matter, greenhouse gases and the wider health of freshwater ecosystems. Microbial communities are sensitive to a range of chemicals such as antibiotics, antivirals, fungicides which make their way into freshwaters. This project is about identifying new approaches for understanding the impacts of micropollutants on freshwater ecosystems and how freshwater microbes respond to the pressures of chemical pollution and climate, socioeconomic and land use changes in the future.

Dr Read said: “Our work will prioritise the types of chemicals that are going to have an impact on microbial communities. We will develop new indicators based on genetic analysis of these species to understand how chemicals may be impacting on the function and classification of the species. We are working with the Environment Agency, the Rivers Trust and water companies to develop tools to predict how the health of freshwater ecosystem will change in the future and help us manage rivers more effectively.”

There are two ways that micropollutants make their way into freshwaters

• We flush household chemicals down the sink or toilet and they make their way into wastewater treatment works. Some chemicals can pass through these treatment works unaffected or not completely degraded and they make their way into the environment
• Agricultural chemicals that we use on land such as insecticides and fungicides plus road run off.

We can have thousands of chemicals getting into our rivers and the challenge is understanding which types are important, how do they interact with one another and at what concentration do they become a threat.

We can have thousands of chemicals getting into our rivers and the challenge is understanding which types are important, how do they interact with one another and at what concentration do they become a threat.

PACIFIC uses a range of approaches from controlled experiments in laboratories to observations in the field. Outdoor samplings are being carried out upstream and downstream of wastewater treatment works at The River Avon in Bristol and The Thames to examine the composition and functioning of microbes and pollutants. The team of scientists measure the microbes that live in the rivers as an indicator of whether it is healthy – similar to how we measure the microbes that live in our gut. An unhealthy or unbalanced microbial community within rivers can be caused by exposure to antimicrobials or other chemicals or stressors such as a rise in temperature.  The project looks at the range of species or measures how they function such as their growth rates of their levels of antimicrobial resistance genes their produce to adapt to the chemicals.

A final part of project is to work at national scale forecasting into the future looking at what would happen as a result of climate, hydrological and land use and socio ecological changes. For example if we have hotter, drier summers then water dilutions would get less and that may have impact on the quality of our rivers.