A person holds a lit candle and a card during a ceremony to mark the one-year anniversary of the Deepwater Horizon tragedy, in New Orleans, Louisiana April 20, 2011. [Photo/Agencies]

John Koeferl of New Orleans (R) joins members of the Sierra Club, a grassroots environmental organization, during a ceremony to mark the one-year anniversary of the Deepwater Horizon tragedy, in New Orleans, Louisiana April 20, 2011. [Photo/Agencies]