By Erich Wagner (File photo)

Alexandria officials are keeping a close eye on an investigation by state and federal agencies into an oil sheen that appeared along the Potomac River last week.

City spokesman Craig Fifer said on February 3, the Alexandria Fire Department received reports of a sheen stretching for eight miles along the Potomac River. The sheen previously had been reported upstream in D.C. on February 2 and at Reagan National Airport on February 1. Officials checked a number of locations along the city waterfront and confirmed no oil had reached the shore on February 4.

Fifer said that a follow-up check of Alexandria’s shoreline Monday again confirmed that the city remains so far unaffected.

“We did check the shoreline again this morning,” Fifer said Monday. “There was no observable sheen or any impact to the environment. Alexandria doesn’t get its drinking water from this area, so we are not really a lead agency at this time.”

The sheen is the subject of an investigation and joint cleanup effort led by the U.S. Coast Guard, the D.C. Department of Energy and Environment and the Virginia Department of Environmental Quality. And the U.S. Fish and Wildlife Services are on hand to help care for any animals or waterfowl affected by the incident.

Last week, officials traced the sheen to Roaches Run Waterfowl Sanctuary in Arlington and deployed a series of containment boons at Gravelly Point, also in Arlington. D.C. DOEE spokeswoman Julia Robey Christian said the effort has proven effective so far in tamping down on the sheen.

“We had been chasing this large rainbow sheen for eight miles over several days leading up to this, but after containing it, that sheen has dissipated,” she said. “Since then, they’ve focused on investigating the source. Preliminary results of tests [on the substance] came back and showed that the material was some kind of heavily weathered fuel oil, but that can still be any number of things. It doesn’t rule anything out at this point.”

An announcement about the full results of the tests investigating the type and source of the oil was scheduled for Wednesday afternoon, after the Times’ print deadline.

U.S. Coast Guard Petty Officer David Marin said officials have narrowed the source of the sheen down to the region’s sewer systems.

“We’ve been checking the storm drain systems, and we’re trying to track down to see if there’s any responsible party and to track down the location of where this oil may have come from,” Marin said. “[All] of the locations we’ve checked have been in Arlington.”

Officials continue to recover oiled birds, which are being sent to Tri-State Bird Rescue and Research in Delaware to be cleaned and rehabilitated. As of Sunday, officials had recovered 19 geese and one duck in need of treatment, but they said the numbers are growing every day.

“One of the issues we’re having just in the last hour now is we have identified three great blue herons that have been oiled,” said Christian.

To combat the prospect of more birds becoming affected by the sheen as they enter Roaches Run, Marin said the Coast Guard plans to employ a technique through Friday to deter birds from entering the area: pyrotechnics.

“Basically, it’s [using] firecrackers and bottle rockets,” Marin said. “It doesn’t harm the birds, and they actually already use them sometimes at Reagan Airport. The popping noise just keeps them away, and we’ll keep doing that until the oil fully dissipates.”

“The use of small pyrotechnics to deter birds from using particular areas during an oil response is a commonly employed technique utilized by wildlife biologists to minimize the negative impacts of oil to birds and other wildlife,” said Peter McGowan, a wildlife biologist with the U.S. Fish and Wildlife Services, in a statement.