Road discharge found polluting rivers is "likely to be tip of the iceberg"

EA says it is trying to reduce pollution from roads, including working with National Highways to introduce pollution mitigating schemes

Road pollution is unleashing a toxic cocktail of heavy metals, hydrocarbons, microplastics and other chemicals into England’s rivers, but no one is monitoring their effect on wildlife or public health, according to analysis by The Guardian and Watershed Investigations.

Dirtied rainwater from the main road network is discharged from over 18,000 outfalls and around 7,700 soakaways managed by National Highways. Its recent assessment revealed that 1,236 of these had “a potential high risk of pollution” and “145 have a verified high risk of pollution and require mitigation”, while the rest had a “potential high risk” of “polluting the water environment”.

The analysis found around 70 of these sites are in legally protected areas, important for habitats or wildlife, while roughly 250 are within 1km of a protected site. Hundreds more discharge to rivers and land without formal protection, and such outfalls are not subject to environmental permitting regulations.

“This is likely to be the tip of the iceberg, because National Highways are responsible for just 3% of the road network and there’s over 25,000 outfalls and soakaways on that,” said Lena Hosea, founder of Watershed Investigations. “But all the other roads are under the responsibility of local authorities, so there’s a lot more pollution outlets we don’t know the locations of.”

According to National Highways, they do not regularly monitor runoff as it can vary depending on rainfall and river flows. They also said monitoring would not be practical or offer good value, and instead developed a predictive tool to determine scenarios where the risk of impacts on water quality was unacceptably high.

“National Highways wants to see a connected country and a thriving environment,” said Stephen Elderkin, Director of Environmental Sustainability at National Highways. “We are committed to addressing all of our high-risk water outfalls by 2030 and our Water Quality Plan 2030 sets out a high-level programme of work to achieve this.”

Elderkin says that as part of their continued commitment to protecting the water environment, National Highways has invested in a research programme to understand the risk of pollution from microplastics in road runoff.

“The Environment Agency should be measuring this pollution and regulating the discharges to make sure that they don’t cause environmental harm.”

Jo Bradley, a former Environment Agency (EA) officer who runs the Stormwater Shepherds not-for-profit said: “Road runoff contains metals and organic compounds that are toxic to humans and to the creatures that live in our rivers and seas. The runoff enters rivers and streams every time it rains, and no one is measuring the pollutant levels or the environmental impact. The Environment Agency should be measuring this pollution and regulating the discharges to make sure that they don’t cause environmental harm.”

An Environment Agency spokesperson said: “While highway outfalls are not directly regulated by the Environment Agency, we continue to work with the government and partner organisations to reduce pollution from our roads.

“This includes working closely with National Highways to influence their Road Investment Strategy to include pollution mitigating schemes on their priority list of outfalls and on joint incident response strategies to minimise the risk of pollution arising from road traffic accidents.”

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