UPDATE
(December 16, 2016)

• Throughout the incident, all drinking water test results have been negative (non-detect/absent) for sheen chemicals or other contaminants. 
• Water sample testing was conducted by WSSC, MDE, EPA Region 3 Ft. Meade Laboratory, EPA PHILIS mobile laboratory, Maryland State Laboratory, DC Department of Forensic Services, Fairfax Water, the Washington Aqueduct, and commercial laboratories.
• EPA found no damage to wildlife to be addressed. Shoreline damage is being mitigated by cleaning crews.
• All regional health officials were briefed and participated in regional calls.
• Emergency management officials, public information officers (PIOs), and fire marshals participated in regional utility calls and received all water-PIO information and materials.
• Booms remain in place around all Potomac utility intakes.

UPDATE
(December 6, 2016)

On Monday evening, officials with the U.S. Environmental Protection Agency (EPA) Region 3 for the Unified Command released the U.S. Coast Guard sampling results which show the source of the sheen on the Potomac River is from the NRG Dickerson Power Plant. The discharge, largely dissipated, is estimated to be less than 150 gallons. 

All utility drinking water samples are negative. Utilities will continue to protect drinking water through continued sampling and keeping booms around drinking water intakes. Regional water utilities will continue these actions until all remnants of the sheen are gone and state and federal agencies can ensure water quality in the Potomac River.

Unified Command, led by EPA Region 3, will now include representatives from NRG. All federal and state agencies are working to confirm the oil’s path from the Dickerson facility to the River, make repairs, and clean any residual oil. 

• EPA Press Release: NRG Dickerson Plant Found to be Source of Potomac River Sheen
• WSSC Monday Update

UPDATE
(December 2, 2016)

Almost no sheen was detected by the U.S. Coast Guard and U.S. Park Police during morning flyover. The investigation is ongoing. Booms are deployed at Fairfax Water, the Washington Aqueduct, WSSC, Leesburg, and Rockville intakes. Utilities continue to monitor for sheen at and near intakes, sample water, and add activated carbon. 

• Fairfax Water update

UPDATE
(November 30, 2016) - EPA Region 3, the U.S. Coast Guard, and the Maryland Department of the Environment (MDE) continued source investigations. Water systems continue to add to their stored water supply.

• WSSC Wednesday update

UPDATE
(November 29, 2016) - All water systems along the Potomac River in metropolitan Washington continued to monitor source water and drinking water quality. The investigation is ongoing. Lab testing is in progress to identify the contaminant. Water systems and jurisdictions will continue to provide updates about the response, and will notify residents if additional actions are needed.  

• WSSC Tuesday update
  
   

NEWS RELEASE
Washington, D.C. (November 28, 2016) - State and regional officials reported a sheen on the surface of the Potomac River on Sunday, November 27, 2016. Officials are monitoring water quality and the time it takes the plume to reach drinking water intakes. Potential changes to downstream water quality are being evaluated and preparations are in place to protect the region’s drinking water.

Water systems involved with the response are DC Water, Fairfax Water, Frederick County, the Town of Leesburg, the City of Rockville, Washington Aqueduct, and the Washington Suburban Sanitary Commission. At this time, officials believe the event is unlikely to disrupt water supplies in the metropolitan Washington region. Actions to protect the region's drinking water include increasing water quality testing in the river, closing and alternating intakes, adding activated carbon to boost drinking water treatment, and placing protective booms around intakes. Water systems and jurisdictions will provide updates about the response and notify residents if additional actions are needed. Customers can contact their drinking water provider or check the COG website for additional information.

The U.S. Environmental Protection Agency Region 3 is the lead response agency. Actions to protect the regional water supply and public health are being coordinated and implemented by water systems on the Potomac River, working closely with the U.S. EPA, Maryland Department of Environment (MDE), Virginia Department of Environmental Quality (VDEQ) & Department of Health (VDH), District Department of Energy and the Environment, Interstate Commission on the Potomac River Basin, COG, and the U.S. Coast Guard.