Coast Guard to use dye to investigate mysterious oil spill coating Potomac River

The Potomac River flows under the Memorial Bridge in Washington, United States. ©  Gary Cameron
Federal, state and local authorities are investigating an unidentified oily sheen covering a large swath of the Potomac River. The US Coast Guard will dye the river in order to find out where the spill came from.

The substance could be seen Friday on an eight-mile stretch of the Potomac River near Washington DC, including at Virginia’s Roaches Run Waterfowl Sanctuary, which is identified as the area where the oil started appearing. At least 21 geese and several ducks were found to be coated with oil, according to NBC Washington.

The Coast Guard has since erected floated barriers and absorbent material at sites where the oily sheen was seen to be entering the river. As of Monday, the service was working with Virginia’s Department of Environmental Quality and the District’s Department of Energy and the Environment to conduct a dye test at Roaches Run to trace the discharge through the storm drain network.

“We want to inform people in an attempt to mitigate concern by the public, who may see the dye in the water and mistake it as something else,” Coast Guard Commander Michael Keane said in a statement.

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The authorities said they do not know if the oil came from a spill at a single site, or if it was runoff from streets caught up in the snow left over from January’s blizzard, according to The Washington Post. While the oil sheen, first spotted Wednesday, was believed to have mostly dissipated over the weekend, a field team announced Sunday that a possible new source was draining into the waterfowl sanctuary.

A Coast Guard laboratory is testing samples of oil taken from Roaches Run in an attempt to identify where it came from. The samples are being tested against those from a 31,500-gallon spill of mineral oil from a Dominion Virginia Power substation.

Dominion is cooperating, but has said there’s no evidence that the recent spill came from their facilities.

The oily substances didn’t have any negative impact on drinking water in the area, officials said. However, environmentalists are concerned that the spill may cause damage to the Potomac’s fish and wildlife.