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

One of Britain's largest oil refineries has been linked to dozens of pollution incidents over a two-year period, according to internal documents obtained by investigative journalists and shared exclusively with the BBC. The records suggest that EET Fuels, the company operating the Stanlow refinery in Ellesmere Port, Cheshire, discharged toxic chemicals and oil into local waterways and the Mersey Estuary on numerous occasions during 2023 and 2024, in what regulators have determined amounted to repeated breaches of its environmental permit.

Stanlow is the second-largest refinery in the United Kingdom and one of only four still operating in the country. It processes approximately 10 million tonnes of crude oil annually, supplying roughly 18% of the fuel used for road transport across Britain. The site is owned by EET Fuels, formerly known as Essar, which purchased the facility 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, but it is legally obligated to minimise pollution and protect both the environment and public health.

The documents, uncovered by environmental journalists from SourceMaterial, indicate that permitted limits for chemical releases were exceeded hundreds of times across 2023 and 2024. The Environment Agency, which regulates industrial pollution in England, concluded that EET Fuels violated its permit conditions on 58 separate occasions during that period. Such breaches could constitute illegal offences under environmental law. The Environment Agency has confirmed it is investigating the matter.

Among the pollutants reportedly released were cyanide, benzene, and heavy oils. These substances entered the air and flowed into local waterways including Thornton Brook and the River Gowy, both of which connect to the River Mersey Estuary. According to the documents, sulphur dioxide was emitted into the atmosphere at levels seven times higher than permitted, cyanide entered waterways at more than eight times the allowed concentration, and oil was discharged at more than thirteen times the permitted limit.

The Mersey Estuary holds significant ecological importance. It is designated a Site of Special Scientific Interest (SSSI) and serves as a habitat for endangered species, including dolphins, as well as a breeding ground for rare birds. Charlotte Harris, chief executive of the Cheshire Wildlife Trust, explained that species such as dunlin, black-tailed godwit, and redshank travel from around the world to feed and rest in the wetlands surrounding the river. She noted that these populations have only been able to recover because conservation organisations have spent years cleaning up pollution left behind by previous industries in the region.

The estuary has also seen the return of Atlantic salmon, while the critically endangered European eel migrates up the Mersey and into the River Gowy each year to breed. Harris warned that chemical pollution does not remain confined 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. Her comments underscore the potential for industrial discharges to affect wildlife and ecosystems far beyond the immediate vicinity of the refinery.

One particularly serious incident occurred in July 2023, when rainwater contaminated with oil leaked from the Stanlow site. The Environment Agency classified the event as "significant." Its report noted a substantial number of complaints from local residents about odours, and subsequent investigations indicated that the oil had contaminated groundwater supplies. In response, EET Fuels told the BBC that the quantity of oil lost was on a "low scale" and that the contamination "was strictly localised to two boreholes, all well within the Stanlow site itself."

A second major spill took place on 12 September 2024, when oil was again released from the facility. Over a 36-hour period, more than one tonne of oil flowed into Thornton Brook and eventually reached the Mersey Estuary. EET Fuels reported the incident to authorities, but nearly two weeks passed before the company provided an estimate of the volume spilled. This delay represented a further breach of regulations, which require such information to be submitted within 24 hours. An emergency response team was assembled, involving the Environment Agency, Natural England, local port authorities, and the Fisheries Authority, according to meeting documents.

Natural England, the body responsible for regulating SSSIs, expressed concern about the ecological consequences. In one meeting, the organisation stated: "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 was deployed to assess the damage, revealing that oil had spread more than a mile downstream and that "there was brown discolouration around the reedbed." Footage captured wading birds, including the red-listed dunlin, in the affected area.

The revelations add to a growing record of environmental compliance problems at Stanlow. Earlier this year, EET Fuels pleaded guilty to 12 charges of breaching environmental law between 2018 and 2020. The newly disclosed documents suggest that pollution incidents continued well beyond that period. The company has stated that it "takes its environmental responsibilities extremely seriously," but the frequency and severity of the reported breaches raise questions about the effectiveness of oversight and the adequacy of protections for the Mersey Estuary.

Environmental groups and local communities are likely to press for tougher enforcement as the Environment Agency's investigation proceeds. The case highlights broader tensions between the UK's reliance on domestic refining capacity and the environmental costs associated with heavy industry. With only four refineries remaining in the country, Stanlow plays a strategically important role in fuel supply, yet the documents suggest that its operations have repeatedly come at the expense of water quality, air quality, and protected wildlife habitats.

For residents living near the refinery, the reports may reinforce long-standing concerns about odours, groundwater contamination, and the health of local rivers. For conservationists, the incidents underscore the vulnerability of the Mersey Estuary, a landscape that has been the focus of decades of restoration work. As the investigation continues, the outcome could shape how regulators balance industrial production with environmental protection in one of Britain's most important estuarine ecosystems.