TOLEDO, Ohio (AP) — Underwater contractors are being sent to Lake Erie to search for the source of what appears to be a petroleum leak coming from a century-old sunken barge found recently in the lake near the U.S.-Canadian border, the U.S. Coast Guard said Sunday. Shipwreck hunters think the leaking solvent is from a tanker barge that went down near Ohio's Kelleys Island during a storm nearly 80 years ago. It would be a significant discovery if the vessel turns out to be the Argo, one of 87 shipwrecks on the federal registry created two years ago to identify the most serious pollution threats to U.S.