Mystery Oil Sheen on Potomac Identified, EPA Says

That mystery sheen on the Potomac River, first reported more than a week ago, has finally been identified. The Unified Command, led by the U.S. Environmental Protection Agency, has identified the NRG Energy's Dickerson Power Plant in Maryland as the source of the sheen that showed up on the Potomac River more than a week ago, the U.S. Environmental Protection Agency announced Monday.

The Unified Command consists of EPA, the U.S. Coast Guard, Maryland Department of Environment, Virginia Department of Environmental Quality, Virginia Department of Health, Washington D.C. Department of Energy and the Environment, and NRG.

U.S. Coast Guard laboratory analysis on Monday of sheen samples taken from the Potomac River identified the product as lubricating oil, matching samples taken at the Dickerson Power Plant and at Whites Ferry. NRG Energy officials have been notified and agreed to join the Unified Command as the responsible party, the EPA said. All Unified Command parties are working to remedy the problem and ensure protection of public health, according to the EPA. The discharge, which has largely dissipated, was less than 150 gallons.

The EPA did not say how the discharge got into the river.

On Sunday, Nov. 27, NRG notified and began working with the EPA and other Unified Command agencies to identify the source, the EPA said. By Dec. 2, the sheen had diminished considerably, with nominal sheen sighted in two locations – south of Whites Ferry and near NRG’s Dickerson power plant.

On Dec. 4, shoreline assessments completed by foot and then by boat from Whites Ferry up to the Dickerson Plant revealed degraded sheen in these same areas. There is no evidence of new sheen, the EPA said.

Inspections at all locations where booms are in place to protect drinking water intakes confirmed that the booms continue to divert the degraded sheen away from intake locations, according to the EPA. Inspection and maintenance of the booms will continue, as will sampling at water intakes by the water utilities. EPA continues to support requests for analyses performed by the agency’s mobile lab on-site at the Dalecarlia Water Treatment Plant.

Based on information provided to EPA during daily conference calls with the water utilities, none of the intakes actively used by water utilities have revealed spill-related constituents, the EPA reported. Treated water is also being sampled by water utilities to determine if spill-related constituents are present.

PHOTO: DC Department of Energy and Environment