It's been four years since the BP Deepwater Horizon spill in the Gulf of Mexico.
You'll remember the images of oil soaked birds trapped in the sludge and clean up crews walking along the shoreline covered head to toe in white protective suits. Eleven people lost their lives in the accident as an estimated 5 million barrels of oil gushed into the sea for almost three months.
But years later, BP still hasn't cleaned up the mess. That's the assessment of researchers from UC Santa Barbara and UC Irvine who recently did a survey of the damage. They found a 1,200-square-mile "bathtub ring" of oil on the ocean's floor. That's about the size of Yosemite National Park.
Dave Valentine is lead author of the study and geochemist at UC Santa Barbara and he joins the show to talk more about it.