TOLEDO, Ohio -- A dive team is searching for the source of what appears to be an oil-based substance leaking from a barge that sank in Lake Erie during the 1930s.
The recently discovered barge is one of nearly 90 shipwrecks on a federal registry created two years ago to identify the most serious pollution threats to U.S. waters.
Most of those wrecks are along the Atlantic seaboard and were sunk by German submarines during World War II.
Other sunken ships thought to be holding oil are scattered along the Pacific Coast and in the Gulf of Mexico just off the Florida and Louisiana shorelines.
Experts say the shipwrecks aren't "ticking time bombs." But they do think it's only a matter of time before oil starts leaking from the wreckage.