The U.S. Coast Guard is still investigating what caused a grain barge to drift away from its moorings and into the shipping channel on a river in the Pacific Northwest late last week, a Coast Guard spokesman said Tuesday.
The 12.8-metre wide, 74.7-metre long barge was later safely retrieved and there was no reported impact on shipping.
"We're still investigating and hoping that someone will come forward with more information," said USCG Petty Officer Third Class Katelyn Tyson.
The unmanned and unlit barge was found drifting late Friday night on the Columbia River between Portland, Oregon, and Vancouver, Washington, by the tow boat Lori B, which retrieved it and hauled it back to a staging area.
The barge was reported missing by workers at a nearby Tidewater Barge facility. A Tidewater employee found that ratchets meant to hold the barge in place appeared to have been intentionally loosened, the Coast Guard said.
Some critics accused striking port workers represented by the International Longshore and Warehouse Union (ILWU), which is locked in a year-long contract dispute with grain exporters in the region over work rules and pay.
But the Coast Guard said there was no evidence that ILWU workers were involved and the union also denied involvement.
"The manner in which the barge broke free from the dock is pure speculation... The union had nothing to do with it," said ILWU spokeswoman Jennifer Sargent said.
The Pacific Northwest is a critical outlet for U.S. grain exports. Nearly half of all U.S. wheat shipments and about a quarter of total U.S. grain and oilseed exports exit the country via the Pacific Northwest.
-- Karl Plume reports for Reuters from Chicago.