After dropping off building supplies for a taconite plant near Nashwauk, the last oceangoing ship of the year departed Duluth on Saturday.

The Palmerton, Duluth's last "saltie" of 2014, sailed under the aerial lift bridge and out into Lake Superior at 12:26 a.m. Saturday, according to the Duluth Seaway Port Authority. The 436-foot Antigua-flagged ship is now on a 2,342-mile journey to the Atlantic Ocean and must get through locks at Lake Erie and Lake Ontario before they close on Dec. 31.

Adele Yorde, spokeswoman for the port authority, said the Palmerton was dropping off supplies for the Essar Steel plant, which is under construction east of Grand Rapids, and was empty when it left the port.

"It left light when it left here," she said. "They talked about making one last stop in Erie, Pa."

The last saltie of the year departing Duluth is a sure sign of the deep freeze of winter, but shipping season isn't quite over for the Twin Ports. Lakers, ships that stay within the Great Lakes, will continue to sail out of the Port of Duluth-Superior until Jan. 15 as they rush to stock steel mills to the south with enough iron ore to get through the winter.

Despite the most brutal winter in decades to start the 2014 season, year-to-date shipments through the Port of Duluth-Superior have nearly caught up to where they were at this time last year, thanks to plenty of rain, which allows ships to carry more cargo without scraping against the bottom in shallow spots.

"Higher water levels across the system this year helped tremendously in making up time and tonnage," said Vanta Coda, the Duluth Seaway Port Authority's executive director, in a statement. "Thousand-footers, for example, were able to load to another foot deeper draft, allowing some 3,000 additional tons of iron ore or coal on every downbound delivery."

Shipments of iron ore to domestic and Canadian steel mills are up nearly 6 percent compared to a year ago. Increases in commodities like limestone and salt, plus general cargo shipments, helped offset declines in coal and grain shipping this season.

Though ice has already formed on Lake Superior and elsewhere in the system, shipping has not been significantly impacted so far this winter.

Adam Belz • 612-673-4405 Twitter: @adambelz