TOLEDO, Ohio (AP) — The U.S. Coast Guard is leading efforts to find a leak of what it believes is a petroleum-based substance coming from a sunken barge on the bottom of Lake Erie near the U.S.-Canadian border.
What makes that so challenging goes beyond just the location of the wreckage.
Among the questions — what is leaking, where is it coming from, how much remains and is there anything else that could a pose a danger on the recently discovered tanker barge 45 feet below the lake's surface.
While the barge's identity is uncertain, shipwreck hunters and the Coast Guard suspect it's the Argo, among 87 shipwrecks on a federal registry created two years ago to identify the most serious pollution threats to U.S. waters. The Argo is among five such wrecks within the Great Lakes but is the only one whose location hasn't been confirmed.
A shipwreck hunter spotted the vessel in late August. Reports from divers last week say the steel barge is largely intact and upright, covered by a thick coating of invasive zebra mussels.
Historical documents contain conflicting information about what the Argo was carrying when it sank during a storm in 1937. A report produced by the National Oceanic and Atmospheric Administration in 2013 said it was believed to be carrying 100,000 gallons of crude oil along with benzol. Research also indicates the cargo was an unknown petroleum-based solvent that was perhaps a by-product from a steel mill.
Without knowing the vessel's identity or its cargo, a Coast Guard team began taking air samples at the site Monday to see if it could determine the substance. The Coast Guard also wants to make sure the area is safe before underwater contractors begin searching for the source of the leak and trying to plug it. That work could begin as early as Tuesday.
Because there have not been widespread reports of a leak in the area, it's most likely a small or intermittent release. But the Coast Guard says it can't verify that without a closer look.
Contractors hired by the Coast Guard to examine the vessel did not see evidence of a leak nearly a week ago, but two days later divers with Cleveland Underwater Explorers described smelling fumes in the air and seeing a blob hit the surface and break into little pieces.
That led the Coast Guard to warn boaters to stay away and speed up plans to assess the wreckage.
THE NEXT STEPS
Once the area is safe for divers, the first priority is to find and seal the leak. The challenge is that it appears to be a colorless solvent that evaporates quickly once it reaches the surface and visibility is low in the lake.
After that, divers will need to determine how much cargo is onboard and whether it is hazardous and needs to be pumped out. It's possible that some has escaped slowly over years or even decades. One way to find out would be to drill a hole in the tank and sample whatever is inside without spilling it.