It 's not clear whether the hurricane swept tar balls ashore or exposed them under the sand , U.S. Coast Guard Petty Officer Bill Colclough said . Preliminary tests from Louisiana island show oil from BP spill . Tar balls and an oil mat have been found since Hurricane Isaac . Score: 7
Preliminary tests from Louisiana island show oil from BP spill . Tar balls and an oil mat have been found since Hurricane Isaac . Score: 7