Documents Reveal Stanlow Oil Refinery Exceeded Toxic Pollution Limits Dozens of Times

One of Britain's largest oil refineries has repeatedly released harmful pollutants into surrounding waterways and the atmosphere, according to internal documents obtained by investigative journalists. The records, shared exclusively with the BBC, indicate that EET Fuels — the company operating the Stanlow refinery in Ellesmere Port, Cheshire — breached its environmental permit conditions on 58 separate occasions during 2023 and 2024.

The refinery, which processes approximately 10 million tonnes of crude oil annually, supplies roughly 18% of the UK's fuel for road transport. It is one of only four remaining oil refineries in the country and was purchased from Shell by the company then known as Essar in 2011 for £842 million. The firm later rebranded as EET Fuels.

Under its operating permit, the company is allowed to discharge controlled quantities of oil and chemicals into the air and local waterways. However, it is legally obligated to minimise pollution and any potential harm to human health. The Environment Agency (EA), which regulates the site, has determined that the permitted thresholds for chemical releases were exceeded hundreds of times across the two-year period, with 58 instances formally classified as breaches of permit conditions — conduct that could constitute a criminal offence.

The documents, uncovered by environmental journalists from SourceMaterial, describe spills involving dangerous substances including cyanide, benzene, and heavy oils. These pollutants entered local waterways such as Thornton Brook and the River Gowy, both of which flow into the River Mersey Estuary. The estuary holds Site of Special Scientific Interest (SSSI) status and provides critical habitat for 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 affected area, noting that species such as dunlin, black-tailed godwit, and redshank travel from around the world to feed and rest in the wetlands surrounding the Mersey. She explained that these habitats only became viable again after years of remediation work by organisations like the Wildlife Trusts to address pollution left behind by previous industrial activity. Atlantic salmon have returned to the river, Harris added, and the critically endangered European eel migrates up the Mersey and into the River Gowy each year to breed.

According to the EA documents, pollutant releases included sulphur dioxide discharged into the air at levels seven times higher than permitted, cyanide entering waterways like the Gowy at more than eight times the allowed concentration, and oil at over thirteen times the permitted limit. These figures suggest a pattern of systemic exceedances rather than isolated incidents.

One notable event occurred in July 2023, when rainwater contaminated with oil escaped from the site. The EA classified the incident as "significant" and recorded a substantial number of complaints from local residents regarding odours. Subsequent investigations indicated that the oil had contaminated groundwater supplies beneath the facility. In response, EET Fuels stated that the quantity of oil lost was on a "low scale" and remained "strictly localised to two boreholes, all well within the Stanlow site itself."

A more severe incident took place on 12 September 2024, when oil was again released from the site. Over a 36-hour period, more than one tonne of oil flowed into Thornton Brook and subsequently spread into the Mersey Estuary. Although EET Fuels reported the spill to authorities, the company took nearly two weeks to provide an estimate of the volume released — a delay that itself constituted another regulatory breach, as such estimates are required within 24 hours.

The response involved an emergency team comprising the EA, Natural England, local port authorities, and the Fisheries Authority, according to meeting records. Natural England, which oversees SSSI protections, warned during one meeting that the contamination would likely affect vegetation and salt marsh habitats, and that there remained a probable risk of birds ingesting the oil.

A drone survey conducted to assess the extent of the damage revealed that oil had spread more than a mile downstream, with brown discolouration visible around the reedbed. The footage also captured wading birds, including the red-listed dunlin, in the contaminated area.

Harris stressed that chemical pollution in river systems is rarely contained to a single location. "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," she said.

EET Fuels has maintained that it "takes its environmental responsibilities extremely seriously." The Environment Agency has confirmed it is investigating the breaches, though no enforcement action has yet been announced. The company previously pleaded guilty this year to 12 charges of breaching environmental law between 2018 and 2020, indicating a history of compliance failures at the site.

The revelations raise questions about the adequacy of regulatory oversight at Stanlow and the cumulative impact of repeated pollution events on protected ecosystems. With the Mersey Estuary serving as a vital habitat for migratory birds and aquatic species, continued contamination could undermine decades of conservation and cleanup efforts. The EA's ongoing investigation will determine whether further legal action follows.