NOAA Report Examines Oil Pollution Threat From Shipwrecks

14 May, 1942, U. S. Army Air Corps photographs of the burning tanker Potrero del Llano location. Photo Credit: Images courtesy of National Archives, College Park, MD

Report presented to U.S. Coast Guard for use in contingency plans

NOAA on Monday presented the U.S. Coast Guard with a new report on the pollution threat posed by the thousands of shipwrecks scattered across the U.S. seafloor.

The report, which is part of NOAA’s Remediation of Underwater Legacy Environmental Threats (RULET) project, identifies the location and nature of potential sources of oil pollution from sunken vessels, which could help oil response planning efforts and in the investigation of reported mystery spills.

In total, NOAA identified 36 “worst case” shipwrecks that could pose a oil pollution threat to the U.S.’s coastal marine resources. Of those, NOAA says, there are 17 that are recommended for further assessment and potential removal of both fuel oil and oil cargo.

The sunken vessels are a legacy of more than a century of U.S. commerce and warfare. They include a barge lost in rough seas in 1936; two motor-powered ships that sank in separate collisions in 1947 and 1952; and a tanker that exploded and sank in 1984. The remaining sites are 13 merchant marine ships lost during World War II, primarily along the Atlantic Seaboard and Gulf of Mexico.

“This report is the most comprehensive assessment to date of the potential oil pollution threats from shipwrecks in U.S. waters,” said Lisa Symons, resource protection coordinator for NOAA’s Office of National Marine Sanctuaries. “Now that we have analyzed this data, the Coast Guard will be able to evaluate NOAA’s recommendations and determine the most appropriate response to potential threats.”

“The Coast Guard is pleased to receive these risk assessments from our partner agency NOAA and looks forward to our continued coordination on the matter of potential pollution associated with sunken vessels in U.S. waters,” said Capt. John Caplis, the Coast Guard’s chief of marine environmental response. “Coast Guard federal on-scene coordinators receiving the risk assessments will carefully review the data and incorporate it into their area contingency plans.”

In 2010, Congress appropriated $1 million for NOAA to develop a list of the most significant potentially polluting wrecks in U.S. waters, including the Great Lakes, specifically addressing ecological and socio-economic resources at risk.  NOAA maintains the internal Resources and UnderSea Threats (RUST) database of approximately 30,000 sites of sunken material, of which 20,000 are shipwrecks. The remaining items are munitions dumpsites, navigational obstructions, underwater archaeological sites, and other underwater resources.

An initial screening of these shipwrecks revealed that 573 could pose substantial pollution risks, based on the vessel’s age, type, and size. This includes vessels built after 1891, when U.S. vessels began using fuel oil; vessels built of steel; vessels over 1,000 gross tons, and any tank vessel.

NOAA says that additional research about the circumstances of each vessel’s loss narrowed that number to 107 shipwrecks. Of those, some were deemed navigational hazards and demolished, and others were salvaged. Most of the 107 wrecks have not been directly surveyed for pollution potential, and in some cases little is known about their current condition.

To prioritize and determine which vessels are candidates for further evaluation, NOAA used a series of risk factors – total oil onboard, type of oil, nature of sinking, etc. – to assess the likelihood of substantial amounts of oil remaining onboard, and the potential ecological and environmental effects if that oil spills.

After this third level of screening, 87 wrecks remained on the list developed for the Coast Guard’s area contingency plans. Among this group, NOAA determined that 36 shipwrecks are candidates for a “Worst Case” discharge event in which the shipwreck’s entire fuel oil and oil cargo would be released simultaneously, and recommended that 17 of these wrecks be considered for further assessment and feasibility of oil removal.

In addition, six wrecks are potential candidates for a “Most Probable” discharge event, where a shipwreck could lose approximately 10 percent of its fuel oil or oil cargo. To date, known oil discharges from shipwrecks are typically in the “Most Probable” category or smaller, NOAA says.

The report, including 87 risk assessments, is not intended to direct Coast Guard activities, but rather provide the Coast Guard with NOAA’s scientific and technical assessment and guidance as a natural resource and cultural heritage trustee.

The Coast Guard, as the federal On-scene Coordinator for mitigating oil spills in the coastal marine environment, the Regional Response Teams, and local Area Committees, as established under the Oil Pollution Act of 1990, will review and incorporate the assessments into regional and area marine environmental response contingency plans. The individual risk assessments not only highlight concerns about potential ecological and socio-economic impacts, but also characterize most of the vessels as historically significant and many of them as grave sites, both civilian and military.

NOAA notes, however, that those funding was intended for oil or vessel removal. Funding for any assessment or recovery operations is dependent upon the unique circumstances of the wreck, including if a wreck still has an identifiable owner. If no responsible party exists, however, the Oil Spill Liability Trust Fund would likely be accessed.

View Report: 2012 Risk Assessment for Potentially Polluting Wrecks in U.S. Waters.