What caused that colorful oily sheen floating on the Schuylkill River Wednesday?
The U.S. Coast Guard claimed it was caused by runoff from a water main break along 28th Street in the Grays Ferry section of the city.
The Philadelphia Water Department, however, disputed that claim.
"The Water Department has investigated and determined that the sheen on the Schuylkill River yesterday was not related to the water main break at 28th and Dickinson," said Water Department spokesman John Digiulio.
The sheen appeared up river from where the water main ruptured. Photos of the slick were also posted to social media hours before the break was discovered.
The oily, rainbow-colored, mass was visible from the Schuylkill River Path throughout the day Wednesday.
Pictures were posted to social networks starting Wednesday morning and by the afternoon, the sheen was visible from NBC10’s Comcast Center camera as it floated around Locust Street.
After NBC10 alerted Mayor Michael Nutter’s office to the possible slick, the city called the Coast Guard and asked them to investigate. The Coast Guard controls the waters below the Fairmount Dam.
The Coast Guard confirmed Thursday that they responded and found runoff debris. They cleared the mess from the water by Thursday afternoon.
"The water department is not aware of what caused this oily sheen, however, we will work with the other agencies involved to investigate this to see if a source can be identified," said Digiulio.
The Coast Guard wasn't aware of any threat to the public from the bright-colored event.
The Region 3 office of the federal Environmental Protection Agency didn't receive any information about the event causing any health hazards, said EPA spokesman David Sternberg.