A member of the Arlington Department of Environmental Services, and Petty Officer 3rd Class Cody Fleshman, of Sector Baltimore’s Incident Management Division, inspects the storm drain system on South Fern Street in Arlington, Va., Monday, Feb. 8, 2016. The agencies are checking storm drain systems as part of an investigation to locate the source of an oil sheen that entered the Potomac River. (U.S. Coast Guard photo by Petty Officer 2nd Class David Marin)