THIS month 15 years ago, the US government declared the Deepwater Horizon oil well sealed, ending a catastrophic leak that spilled 4.9 million barrels (779 million litres, or 311 Olympic-sized pools’ worth) of crude oil into the Gulf of Mexico.
The disaster – which killed 11 people – was the largest marine oil spill in history, unleashing an environmental crisis that by some estimates harmed hundreds of thousands of marine animals and devastated coastal ecosystems.
Now, as of September 2025, that legacy is being fiercely debated as the oil industry prepares to drill even deeper.
Why is BP returning to the Gulf?
Despite the controversy, BP is ramping up its commercial ambition in the Gulf of Mexico again.
The company is developing Project Kaskida, a new deep-water well located 250 miles (402 km) from New Orleans, due to start production in 2029.
When completed, Kaskida may produce 80,000 barrels of oil per day, with potential to access up to 10 billion barrels over its lifetime. It will be the Gulf’s first major oil field since the Deepwater Horizon.
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The project will require drilling deeper than the well that failed in 2010 – nearly 1,798 m to the bottom of the Gulf, then another 9,906 m in the rock.
This move is part of a bigger story: in the years since the Deepwater Horizon spill, the US became the world’s top producer of crude oil in 2018, a mantle the country has held every year since.
What drives the industry’s high risk appetite?
The continued corporate focus on deep-water drilling highlights that the risk appetite of major oil firms remains high. This is driven by two key factors.
First, these locations have long proven a rewarding frontier ground for oil exploration, with governments generally permitting firms to operate there.
In the Gulf of Mexico, for instance, the US government awarded the first new post-disaster deep-water drilling permit in March 2011, less than a year after the Deepwater Horizon spill began.
Second, the world’s oil giants are highly resilient to wide-ranging international risks.
Their scale and profitability, despite fluctuations in oil prices, equip them to absorb major setbacks and respond quickly to new opportunities. Even after incurring tens of billions of dollars in costs and seeing its share price nearly halve in 2010, BP remains a dominant industry player.
What are the main safety and political concerns?
The legacy of Deepwater Horizon, however, is much broader than the fate of one company.
The disaster received massive global attention, with an almost immediate regulatory and political backlash. Soon after the oil spill began, several countries including the US, Canada and Norway declared moratoriums on deep-water drilling.
A decade and a half on, significant concerns continue to be voiced about the safety of deep-water drilling. Several Democratic members of the US Congress have written in collective opposition to the Kaskida project, calling it “an unacceptable threat to Gulf communities, ecosystems, and the climate”.
The legislators highlight BP’s own estimate that a worst-case scenario at Kaskida could release up to four million barrels – “a disaster on par with, or exceeding, the Deepwater Horizon spill”. They also claim that BP “severely underestimates the potential size and duration of a worst-case discharge”.
This political concern is amplified by many non-governmental organisations too. Jackson Chiappinelli of Earthjustice, an environmental organisation opposed to the new BP project, asserts that “the deeper you go into the ocean to drill, the greater the risk of a spill”.
What are the long-term environmental and human costs?
Evidence from other major spills indicates there can be long-term legacy on local ecosystems. A number of species still reportedly have not fully recovered from the 1989 Exxon Valdez disaster, which spilled about 41.6 million litres of oil.
The University of South Florida asserts that multiple fish species have not fully recovered since Deepwater Horizon. The US National Wildlife Federation claims that the impact on wildlife is broader, noting that local dolphin populations, struggling with worsened lung disease and other health issues, could take decades to rebound.
The human cost is also still being measured.
Research from the US National Institute of Health on more than 30,000 workers in the Deepwater Horizon oil spill clean-up found they had an increased propensity for health problems including heart attacks, diabetes, rashes, and other skin conditions.
So what’s next?
In this context, the pro-industry “drill, baby, drill” mantra of the second Trump administration raises broad concerns.
The first is that while scientific and technological innovation can improve safety, completely risk-free drilling is unrealistic, given the remote and challenging nature of the work.
The second concern is that intense international focus on the Deepwater Horizon disaster and earlier ones such as Exxon Valdez can obscure a more chronic problem.
Significant spills occur regularly around the world with far less attention. A 2006 report concluded that Nigeria’s Niger Delta has experienced the equivalent of an Exxon Valdez leak every year for nearly 50 years.
It may have been 15 years since the Deepwater Horizon disaster, but the controversy continues. In the absence of further major disasters in the near to mid-term future, deep-water drilling will likely remain a key part of the landscape for years to come.
The writer is is an associate at LSE IDEAS at the London School of Economics
