"Tar balls? A sheen of crude? Oil mousse? Amateur hour. The real villains of America’s beaches are not the scattered and dissipating mess from the Deepwater Horizon disaster, but the nationwide and relentless releases of disease-causing pathogens — human and animal feces — that reach the shorelines from storm runoff and sewage overflows. In its 20th annual report on the water quality at America’s beaches, the Natural Resources Defense Council finds that “from stomach-turning pathogens to dangerous oil slicks, America’s beaches continue to suffer from pollution that can make people sick, harm marine life and destroy coastal economies,” said the NRDC’s David Beckman."
Sharon Begley reports for Newsweek July 28, 2010.
"Oil Causes 2,200 Gulf Beach Closings, Warnings" (AP)
NRDC Report: "Testing the Waters 2010" 
EPA Beaches Page