Stanlow Refinery Accused of Repeated Toxic Spills into Mersey Estuary, Documents Reveal

One of Britain's largest oil refineries has been accused of breaching its environmental permit dozens of times over a two-year period, according to internal documents shared exclusively with the BBC. The records suggest that EET Fuels, which operates the Stanlow refinery in Ellesmere Port, Cheshire, released toxic chemicals and oil into local waterways, the Mersey Estuary, and even groundwater during 2023 and 2024.

The documents were obtained by investigative journalists from SourceMaterial, an environmental reporting outfit, and passed to the BBC. They detail findings from the Environment Agency (EA), which has confirmed it is investigating the breaches. The regulator determined that EET Fuels, formerly known as Essar, broke its permit conditions on 58 separate occasions across the two-year window—a figure that could amount to illegal offences under environmental law.

Stanlow is the second-largest refinery in the UK and one of only four still operating in the country. It processes approximately 10 million tonnes of crude oil annually, producing around 18% of the fuel used for road transport across Britain. EET Fuels purchased the site from Shell in 2011 for £842 million and holds a permit allowing it to discharge controlled quantities of oil and chemicals into the air and water. However, the permit also obliges the company to take measures to limit environmental pollution and harm to human health.

The EA reports uncovered by SourceMaterial indicate that permitted levels for chemical releases were exceeded hundreds of times during 2023 and 2024. Among the pollutants cited are cyanide, benzene, and heavy oils. Sulphur dioxide was reportedly released into the air at seven times the permitted level, while cyanide entered waterways such as the River Gowy at more than eight times the allowed concentration. Oil was discharged at more than thirteen times the permitted level in some instances.

The pollutants flowed into Thornton Brook and the River Gowy, both of which connect to the River Mersey Estuary. That estuary holds the status of a Site of Special Scientific Interest (SSSI) and supports endangered species including dolphins, as well as serving as a breeding ground for rare birds. Charlotte Harris, chief executive of Cheshire Wildlife Trust, emphasised the ecological importance of the area, noting that species such as dunlin, black-tailed godwit, and redshank travel from around the world to feed and roost in the land surrounding the Mersey.

Harris explained that these habitats have only recovered because organisations, including the Wildlife Trusts, have spent years cleaning up pollution left behind by legacy industry. She pointed to the return of Atlantic salmon to the river and the annual migration of the critically endangered European eel up the Mersey and into the River Gowy to breed. "Where we have chemical pollution the impact isn't just localised," Harris said. "When it enters the river system, that system is highly dynamic and high energy, which means that pollution spreads far and wide really, really quickly."

One incident detailed in the documents occurred in July 2023, when rainwater containing oil leaked from the Stanlow site. The EA classified the event as "significant." Its report noted a "significant number" of complaints from local residents about the smell, and further investigations indicated that oil had contaminated groundwater supplies. In response, EET Fuels told the BBC that the oil lost was on a "low scale" and "was strictly localised to two boreholes, all well within the Stanlow site itself."

A more serious episode unfolded on 12 September 2024, when another EA report says oil was spilled from the site again. Over a 36-hour period, more than a tonne of oil was released into Thornton Brook and spread to the Mersey Estuary. Although EET Fuels reported the incident to authorities, the company took nearly two weeks to provide an estimate of how much oil had spilled—another breach of regulations requiring such information within 24 hours.

An emergency response team was assembled, bringing together the EA, Natural England, local port authorities, and the Fisheries Authority, according to meeting documents. Natural England, which regulates SSSIs, warned in one meeting: "What has gone in there is going to have some impact on the vegetation and salt marsh and there is probably still a risk of ingestion by birds." A drone survey revealed that oil had spread more than a mile down the river, with "brown discolouration around the reedbed." Footage from the drone showed wading birds, including the red-listed dunlin, in the affected area.

The Mersey Estuary hosts the largest group of protected dunlins in the UK, underscoring the sensitivity of the habitat to pollution events. The EA's findings raise questions about oversight of the refinery and the adequacy of self-reporting requirements. While EET Fuels said it "takes its environmental responsibilities extremely seriously," the documents suggest a pattern of repeated permit exceedances over an extended period. The Environment Agency's investigation is ongoing, and it remains unclear what enforcement action, if any, will follow.

The case also highlights the broader tension between industrial operations and environmental protection in the UK, particularly as the country relies on a small number of ageing refineries for a substantial share of its fuel supply. For communities living near Stanlow, the revelations may deepen concerns about air and water quality, while conservation groups warn that the ecological gains made through decades of cleanup work could be undermined by continued pollution. The long-term consequences for the Mersey Estuary's wildlife and for local groundwater resources are likely to remain under scrutiny as the EA's investigation proceeds.