PORTLAND — Coast Guard officials say it appears that someone intentionally set a loaded grain barge adrift on the Columbia River.An earlier report by The Oregonian said the barge was to be unloaded at a terminal that has locked out longshoremen. However, in an email to The Columbian today, Pat McCormick, spokesman for a group of grain-terminal operators that includes United Grain Corp. at the Port of Vancouver, said Barge 550 “was not scheduled for either United Grain or Columbia Grain.”Members of the International Longshore and Warehouse Union have been locked out at United Grain, as well as Columbia Grain in Portland.Tidewater Barge Lines workers reported the barge missing late Friday night. According to a Coast Guard statement, a worker said ratchets used to hold the barge in place appeared to have been intentionally loosened.The crew of a passing tug came upon the unlighted, 252-foot-long barge floating between Portland and Vancouver and towed it back to the staging area where it had been moored.Coast Guard Capt. Bruce Jones says the loose barge could have endangered people or caused a collision.Longshore union spokeswoman Jennifer Sargent says the union had nothing to do with it. A Tidewater spokeswoman did not return calls for comment Monday.