Freshwater? Reviving England’s polluted rivers

A new report published by the BES asks what are the critical actions government should prioritise for freshwater before 2030?

We’ve seen the headlines, read the eye-popping investigations, and heard the exchanges between government, activists and water companies. From Joe Lycett on Channel 4 to the Environment Agency Chair at the NFU Conference last month – the calls for action to help our freshwater ecosystems are getting louder and more urgent. Within the UK, England’s rivers are in the worst health; only 16% classify as having ‘good’ ecological status and the public are increasingly horrified by what they’re hearing.

The Environment Act (2021) sets out much-needed targets for both water quality and biodiversity. The road to achieving these goals, however, is complex, with a nuanced interplay between various stressors and their impact on freshwater ecosystems. Last November, Defra asked the BES to lead a workshop bringing together nearly 40 experts, to help them navigate freshwater policy and set out a list of priorities for the biodiversity evidence programme. The clock is ticking, and we have just six years to achieve the key target to “halt the decline in species abundance by 2030”. Here are the headlines.

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What should government prioritise?

Incentivizing farmers to reduce agricultural pollution

As Alan Lovell pointed out, the uncomfortable evidence is that agricultural pollution is the biggest perpetrator of freshwater pollution. 70% of land in England is farmland, so the priority is to reduce the flow of agricultural pollution into waterways. Options within Defra’s Environmental Land Management Schemes (ELMS) that reduce agricultural run-off need to be heavily incentivised to improve uptake. These should include:

  • promoting regenerative agriculture practices to reduce the use of fertilisers, pesticides and herbicides
  • buffering waterways by farming back from rivers, fencing off watercourses to keep livestock out and planting riparian woodlands

Better regulation of sewage

Of course better monitoring and regulation of wastewater treatment works is essential to reducing sewage overflows. Priorities are ending combined sewage overflow dry spills (spills not caused by heavy rain), and targeting failing sewage plants, particularly those in headwaters to help improve biodiversity along the entire length of a river. Investment is needed to improve wastewater infrastructure and to support nature-based solutions, such as constructed wetlands that facilitate wastewater filtration whilst creating reedbed habitats. These measures will also need to incorporate climate risk.

The BES report is helping us to build our understanding of the pressures on freshwater biodiversity and the actions that will be most impactful for target delivery.


– Dr Emma Jardine, Lead Scientist, Defra

Reducing metal contamination

Across England, many rivers continue to be polluted by industrial metals such as zinc, lead and cadmium. Such metal pollution can have profound impacts on biodiversity because metals have toxic effects and bioaccumulate. Recent research by the Centre for Ecology and Hydrology highlights that reducing zinc and copper contamination can offer significant benefits for macroinvertebrate populations. Targeted actions in urban areas and towards sources of pollution such as transport infrastructure are required to make progress in this area.

PFAS… in our rivers, in our food, in us

But not in the government’s freshwater targets… We need an additional target to encompass reductions in PFAS (Per- and Polyfluorinated Substances, nicknamed “forever chemicals”), pharmaceuticals, plastics, insecticides, pesticides, and other organic chemicals.

Rewilding our waterways? The importance of connectivity

Barriers and modified habitats that limit natural flow and the highs and lows of water cycles (e.g. weirs, riparian habitat removal) can have important consequences for biodiversity. Removing barriers within river and floodplain systems should be a priority so connectivity, functioning and resilience can improve. The recent extension of the River Otter in Devon with its floodplain is a great example of such efforts.

Smaller water bodies need to be included in Defra’s targets. Vital for connectivity, our lakes, ponds, wetlands, canals and slow flowing rivers are often overlooked in monitoring and protection. The pressures and species impacted are different from those in larger waters, but connectivity can be improved quickly by creating new and restoring old ponds.

What can ecologists do?

Updating aquatic biodiversity indicators

The world has changed and the focus on macroinvertebrates as indicators of freshwater ecological quality is outdated. In order to accurately monitor progress, we need to agree on and expand the indicators that we use. A more holistic view of freshwater biodiversity will allow ecologists to build a more accurate picture of the associations between different habitats, pressures, and various aspects of biodiversity (e.g. microbes, algae and invertebrates).

There is no single ‘best’ indicator of change in the water environment and effective indicators should be sensitive to specific pressures, have known uncertainties, and should be readily communicated. We need a diverse suite that collectively provide an assessment of physical, chemical, and biological aspects of the environment and of the action of multiple human stressors. Priority should go to developing indicators for complex chimerical mixtures, microbial communities, non-native species and ecosystem resilience.

We’re ecologists: evidence, evidence, evidence

Increasing monitoring will give us the data to develop and train predictive models that dynamically link water quality with biodiversity indicators. Monitoring should be systematic and use multiple techniques, including new eDNA and high throughput mass spectrometry approaches, machine learning and quality-controlled citizen science.

Sustained investment in monitoring is essential. We need:

  • a better understanding of the many factors that impact the biological status of freshwaters
  • more high-resolution species data to determine which groups of species each water target is likely to impact

Without a monitoring uplift, it will be impossible to know if Defra’s biodiversity targets are achieved, or to trace sources of pollution and resolve conflict over who is responsible.

Waterways are connected by nature and action needs to be joined-up between the four nations of the UK. Only by prioritising actions with the best outcomes for biodiversity, can the government hope to turn the tide on biodiversity loss in England’s rivers. To find out more about what our experts recommended, read the full report.

Read full report

This news story is based on an article in our membership magazine, The Niche, authored by India Stephenson, Dr Steve Thackeray & Dr Emma Ransome.