Stanlow Refinery Repeatedly Exceeded Toxic Pollution Limits, Leaked Documents Show

One of the UK's largest oil refineries has been responsible for dozens of breaches of its environmental permit over a two-year period, according to internal documents shared exclusively with the BBC.

The records, obtained by investigative journalists at SourceMaterial, indicate that EET Fuels — the company formerly known as Essar that operates the Stanlow refinery in Ellesmere Port, Cheshire — discharged pollutants into local waterways, groundwater and the atmosphere on numerous occasions during 2023 and 2024.

Stanlow is the second-largest refinery in the country and one of only four still operating in the UK. It processes approximately 10 million tonnes of crude oil annually, supplying roughly 18% of the nation's fuel for road transport, including cars and trucks. EET Fuels purchased the site from Shell in 2011 for £842 million.

The company holds a permit allowing it to release controlled quantities of oil and chemicals into the air and water. However, the permit also obliges the operator to take measures that limit environmental damage and protect human health. According to the Environment Agency reports uncovered by SourceMaterial, those permitted thresholds were surpassed hundreds of times across 2023 and 2024.

The regulator concluded that EET Fuels breached its permit conditions on 58 separate occasions during the two-year window — conduct that could amount to a criminal offence. The Environment Agency has confirmed it is investigating the breaches.

The documents describe releases involving hazardous substances including cyanide, benzene and heavy oils. These pollutants entered the air and local waterways such as Thornton Brook and the River Gowy, both of which feed into the River Mersey Estuary.

The estuary is designated a Site of Special Scientific Interest and provides habitat for endangered species such as dolphins, as well as a breeding ground for rare birds. Charlotte Harris, chief executive of Cheshire Wildlife Trust, explained the ecological significance of the area, noting that species including dunlin, black-tailed godwit and redshank travel from around the world to feed and roost on the land around the River Mersey.

Harris said that this richness has only been restored because organisations like the Wildlife Trusts have spent years cleaning up pollution left behind by earlier industry. She added that Atlantic salmon have returned to the river and that the critically endangered European eel migrates up the Mersey and into the River Gowy each year to breed.

The Environment Agency's records detail how sulphur dioxide was released into the air at seven times the permitted level, cyanide entered waterways including the Gowy at more than eight times the allowed concentration, and oil was discharged at more than thirteen times the permitted limit.

One incident in July 2023 saw the company breach its permit after rainwater contaminated with oil escaped from the site. The Environment Agency classified the event as "significant". Its report noted a large number of complaints from local residents about the smell, and subsequent investigations suggested the oil had contaminated groundwater supplies.

EET Fuels told the BBC that the quantity of oil involved was on a "low scale" and "was strictly localised to two boreholes, all well within the Stanlow site itself".

A little over a year later, on 12 September 2024, another Environment Agency report records a further spill. 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 the authorities, it took nearly two weeks for the company to provide an estimate of the volume spilled — a second breach, since regulations require such information within 24 hours.

An emergency response team was assembled, drawing in the Environment Agency, Natural England, local port authorities and the Fisheries Authority, according to meeting documents. Natural England, which oversees SSSIs, warned in one meeting that the pollution was likely to affect vegetation and salt marsh, and that there remained a probable risk of birds ingesting the oil.

A drone was deployed to assess the extent of the damage. It revealed that oil had travelled more than a mile down the river and that "there was brown discolouration around the reedbed". The footage also showed wading birds, including the red-listed dunlin, in the affected area.

Harris stressed that the consequences of such pollution are not confined to the immediate vicinity. "Where we have chemical pollution the impact isn't just localised," she 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."

The revelations add to the company's recent environmental record. Earlier this year, EET Fuels pleaded guilty to 12 charges of breaching environmental law between 2018 and 2020. The newly surfaced documents suggest a pattern of permit violations extending well beyond the period covered by those charges.

EET Fuels said in response to the findings: "It takes its environmental responsibilities extremely seriously." The company has not disputed the existence of the Environment Agency reports, though it has characterised the July 2023 oil loss as limited in scale and contained within its own site.

The Environment Agency's decision to investigate the breaches means the matter remains live, with potential enforcement action still to be determined. For communities living near the refinery and for conservation groups working to restore the Mersey's wildlife, the documents raise difficult questions about how effectively one of the country's most important industrial sites is being regulated — and about what is at stake when toxic substances escape into a landscape that has only recently begun to recover from generations of pollution.