It’s officially been five years since BP’s Deepwater Horizon disaster, a well blowout and subsequent oil spill that caused the deaths of 11 men.
A lot has happened since — a massive cleanup effort, scientific research on impacts, civil and criminal court cases galore. But the answers to many basic questions about the historic tragedy remain either unknown and unclear.
On this five-year anniversary, here are five important things we still don’t know about the largest accidental oil spill in world history.
How much oil actually spilled
When people talk about how much oil was spilled during the Deepwater Horizon disaster, there are often two different figures tossed around. Some people use the U.S. government’s figure, which is 4.2 million barrels, or 176 million U.S. gallons. Others use BP’s, which is 3.19 million barrels, or 134 million gallons.
The truth is, no one can really know how much oil was spilled during the 87 days that crude flowed out of the Macondo well and into the Gulf of Mexico. In a January ruling, the federal judge presiding over the Clean Water Act case against BP wrote about the difficulties in estimating exactly how much oil spilled during the disaster in 2010.
“There is no way to know with precision how much oil discharged into the Gulf of Mexico,” he wrote. “There was no meter counting off each barrel of oil as it exited the well. The experts used a variety of methods to estimate the cumulative discharge. None of these were perfect. Because data from the well is limited, every expert had to make some assumptions while performing his calculations.”
How much BP will have to pay
In that January ruling, federal District Court Judge Carl Barbier found that, legally, BP should be held responsible for spilling 3.19 million barrels, a figure that’s about a million barrels less than the U.S. government’s estimate. That was big news for BP, because it decreased the maximum fine the oil giant would be subject to from $18 billion to $13.7 billion.
Still, we aren’t yet sure exactly how much BP will have to pay in Clean Water Act fines — right now, we just know the maximum. BP challenged Judge Barbier’s ruling in February, but the judge hasn’t yet made a final decision as to how much BP is subject to in fines.
BP says that so far, it’s paid out $5 billion to people in businesses in the Gulf that were affected, a figure that’s separate from the Clean Water Act fines. BP, which has tried and failed to challenge the 2012 settlement in the past, says that it’s paid a total of $28 billion on the spill, a figure that includes response, cleanup, claims payments and some restoration work.
How human health has been affected
Questions still remain over the BP oil spill’s overall impact on public health in the Gulf.
Researchers from the National Institute of Health are still working to try to assess how the spill affected Gulf residents, and are working on a 10-year Gulf Long-term Follow-up Study (GuLF STUDY), which involves monitoring the health of 33,000 oil spill cleanup workers for 10 years.
According to preliminary results, these workers felt more physical and mental symptoms in the aftermath of the spill than non-cleanup workers did. But research for the study is still ongoing, and since it aims to compile 10 years worth of data, it will be a few years before we know the final results.
NIH research has also found that residents — not just workers — struggled in the aftermath of the spill. The research is ongoing — it’s in its final year — but so far scientists have found that 30 to 40 percent of the residents in Franklin County, Florida and Baldwin County, Alabama experienced mental health issues in the two years after the spill, compared with 10 to 13 percent of who experienced these issues before. Even now, five years later, incidence of mental health issues is still higher than usual for the area.
A lot of the anger, anxiety, and depression reported by the residents was related to income insecurity. According to the research, the spill destroyed livelihoods for fishermen and others who depended on a healthy Gulf.
How the deep sea will fare
Just after publishing a study on the BP oil spill’s impacts this past summer, Penn State biology professor Charles Fisher told ThinkProgress that he was “worried” about the deep sea.
“The ocean is under a lot of pressure, and the shallows have already felt it very seriously … the deep sea is starting to feel it as well,” he said. “We’re continuing to monitor, because we’re really not sure how it’s going to turn out in the end.”
Fisher was specifically talking about deep sea corals affected by the spill. He and his team had discovered two new coral reefs near the site of the disaster, and found that the negative impacts to those reefs from the spill were greater than expected. Those reefs were farther away and deeper than the one coral reef that had previously been found to have been impacted by the spill — meaning there’s evidence to show that the oil sank deeper than previously thought.
That’s bad for corals themselves, but Fisher said the discovery was more important because coral health can indicate the health of that whole area of the ocean. The deep ocean is mysterious and hard to study, and Fisher said it would be very difficult to know exactly what the effects of oil reaching the deep sea will be.
“What we still don’t know, and what we need to all keep in mind, is that there’s the potential for sub-acute impact,” he said. “In other words, things that might have happened to the corals’ reproductive system — slower acting cancers, changes in the fitness of the animal. These are very hard to detect and they’ll take a long time for us to see whats going on.”
Whether safety standards can really prevent another disaster
New federal regulations on drilling announced over the last few months aim to reduce the risk of future disasters like Deepwater Horizon. And last week, the Obama administration announced proposed regulations that target the reliability of drilling equipment in offshore drilling operations, requiring oil and gas companies to perform tests and maintenance on their blowout preventers, a key piece of drilling equipment.
But some environmental groups say that these new rules are similar to best practices that the industry already has in place, so they don’t go very far in preventing another spill. They also assert that new technologies cannot always account for human error, which have been the underlying causes of other major spills.
The risk of another spill is particularly troubling in the Arctic, a region which, as it melts, has been targeted for drilling by oil and gas companies. In February, the Interior Department proposed its first regulations for oil and gas development in the Arctic Ocean.
But even with new regulations, many are worried about the risks of spills.
“No safety regulations will fix the fact that only 25 percent of the spilled oil from Deepwater Horizon was recovered, burned, or chemically dispersed, leaving 75 percent unaccounted for,” Friends of the Earth said in a statement in March. “The lesson the Obama administration should have learned from Deepwater Horizon is that that only way to keep oil out of our environment is to keep it in the ground.”