In this Sept. 5, 2012 aerial photo, a combination of alluvial clay and tar mats are seen on the shore of Elmer’s Island in the aftermath of Hurricane Isaac, in Jefferson Parish, La. Tests run by Louisiana State University for state wildlife officials confirmed that oil found on Elmer’s Island and Grand Isle matched the biological fingerprint of the hundreds of millions of gallons of oil that spewed from BP’s Macondo well. On Wednesday, BP PLC said oil from its spill had been exposed by Isaac’s waves and that the company would work to clean it up. (AP Photo/Gerald Herbert)