U.S. Coast Guard officials came to Haines Tuesday to investigate an oily discharge that persisted for three days near the Lutak Dock.

Described as a “mystery sheen” by the Coast Guard, ferry terminal workers this week said they suspected the source may have been two barges or a tugboat that had been moored against the dock since Friday, waiting to be loaded with local gravel.

The tugboat’s captain, John “Bigfoot” Eilertsen of Wrangell, said in…