The massive Deepwater Horizon oil spill in 2010 was an environmental calamity of epic proportions. Two hundred and five million gallons of crude oil and two hundred and twenty-five tons of methane spilled into the waters of the Gulf of Mexico off the Louisiana coast. Now a new study by the University of Miami found that the damage is even worse than previously thought.

Horrifying images emerged of the burning oil platform, along with news of the deaths of eleven oil workers on that fateful day. Crude began to spread over the fertile fishing grounds of the Gulf. As the oil spread, even more images haunted the public conscience with oil-covered birds, sea turtles, and marine mammals as cameras brought the reality of this oil spill into the world’s living rooms for eighty-seven days. 

As the oil spill continued unabated, the Obama administration had no easy choices to make on how to respond. The options were all bad. To prevent the oil slick from covering the white sand beaches of Florida's coasts, the decision by the EPA was to spray two million gallons of toxic dispersants onto the sea surface. Where it also spread by winds into coastal communities across Louisiana, the Florida panhandle, and Florida’s Gulf coasts with a fine mist of toxicity that residents had no choice but to inhale. 

The dispersants broke up the oil slick into much smaller pieces but did not reduce the amount of oil in the Gulf. Skimming removed a lot of the surface oil but not all of it, the dispersants caused the oil to sink into the water column, and since that oil was so small that it could not be seen by with naked eye, it was dubbed invisible oil.

Now, nearly ten years after the spill, a new report has found that the invisible oil spread covered more than thirty percent more area than previously thought.

What researchers called “invisible oil” was crude in smaller and lighter concentrations that was flowing around the Gulf of Mexico, not thick enough to be detected by satellites.

Though the oil was lighter in concentration than the crude that the National Response Team was cleaning up on the surface, it was toxic because of the interaction with ultraviolet light, Berenshtein said.

“This photoinduced toxicity means that oil, even in very low concentrations, becomes more toxic than oil alone when UV light is also present,” he said.


Doug Rader, chief ocean scientist with the Environmental Defense Fund, monitored the spill closely and continues to investigate its legacy. He said he agrees with the study’s findings, but believes the impacts spread even farther up the East Coast, and even to Mexico and Cuba.

Rader said that when the surface oil was cleaned up and attention waned from the situation, additional toxic elements of oil not visible to satellites continued to spread at concentrations that caused harm to marine life as far as North Carolina.

He singled out the PAHs, which are particularly problematic because they end up settling on the ocean floor, where worms that feed off sediment eat them. Those worms end up as prey for mid-sized fish like snapper and grouper, which in turn are eaten by bigger fish and mammals, including humans.

“Once [PAH’s] get out in the world, they stay,” Rader said.

Some environmentalists worry the spill hasn’t been fully contained.

Steve Friedman, commodore of the Florida Keys Fishing Guides Association and founding board member of the environmental group Florida Bay Forever, said that when officials dispersed the bulk of the spill and declared the emergency over, he thought the well continued to leak.

“I believe it’s been leaking for years, and is still leaking,” he said.