To evaluate the impact of the oil spill, the trustees conducted
multiple studies, which are outlined here. The detailed findings are
available in the
restoration plan and environmental assessment and
appendices. For additional information, contact
To expedite restoration of injured resources, the trustees and those
responsible for the spilled oil (Potomac Electric Power Company (PEPCO) and ST
Services) worked cooperatively to assess injuries and determine restoration
needs. After conducting multiple reviews and analyses, the trustees determined
that oil affected the following resources:
Overall, 76 acres of marsh were lightly, moderately, or heavily oiled. Wetland
experts quantified the scope and extent of oiling in the marshes along the
Patuxent River and its tributaries by using field observations and aerial
photography. Their estimates were correlated with subsequent measures of marsh
vegetation health in oiled and unoiled areas.
Studies found that 4,976 pounds of benthic invertebrates were lost. Using the
Benthic Index of Biotic Integrity (B-IBI) developed for use in the Chesapeake
Bay, samples were taken in the Patuxent River, Swanson Creek, and Hunting Creek
(the latter as a reference) to determine changes in abundance, biomass, and
The spill resulted in 122 dead diamondback terrapins. There was a 10 percent
reduction in hatchlings in 2000.
Finfish, Shellfish, and Crabs
An estimated 5,432 pounds of finfish, shellfish, and crabs were lost. For all,
mortality was estimated using:
Counts from field surveys and data collected on the number and species of
larvae and eggs present at the time of the spill.
Water column concentrations of petroleum hydrocarbons.
Levels of hydrocarbons in tissues.
Results from toxicity tests.
These data were compared to those in the literature.
Birds (Ospreys, Great Blue Herons, Bald Eagles, and Waterfowl such as Ruddy
The number of lost birds was 696. Scientists visually monitored nests to
document the number of oiled or dead adult, young, and eggs of ospreys, great
blue herons, and bald eagles. For ospreys, data gathered after the spill were
compared to both historical data from the area and data from nests upstream of
the spill area. For great blue herons, these data were compared to a Black
Swamp Creek control site and data in the literature. Bald eagle chicks were
monitored until they fledged.
Many other species, but especially ruddy ducks, were oiled or killed by the
spill. These numbers, as well as qualitative surveys of birds conducted during
the spill, were used to estimate total waterfowl species mortality.
An estimated 376 furbearers, primarily muskrats, were lost. The loss of
furbearing animals was estimated using oiled wildlife mortality counts
maintained by the U.S. Fish and Wildlife Service, data collected by local
trappers, historical surveys from other areas, and the literature.
Lost Human Use
The impacts to recreational fishing, boating, and shoreline use (such as
swimming, picnicking, and wildlife viewing) were assessed, and it was found
that 10 acres of beaches were lightly, moderately, or heavily oiled, and
125,000 river trips were affected. Private losses, such as lost income or
damaged fishing gear, were handled through a private claims process.