The 304-foot Indiana Harbor sits stuck in ice in the St. Clair River awaiting to be freed on Tuesday. The U.S. Coast Guard cutter Neah Bay broke the vessel free later that day. (U.S. Coast Guard)

The Great Lakes shipping season ends Jan. 15. Until then, two Cleveland-based U.S. Coast Guard ice cutters are keeping the channels free of ice, so freighters can deliver goods from port to port.

The Neah Bay and Morro Bay, 140-foot bay class ice-breaking tugs, freed multiple vessels beset by ice in western Lake Erie and the St. Clair River this week, according to a Coast Guard news release.

The polar vortex has covered more than 40 percent of Lake Erie with ice so far this winter. In the next three days, the lake — the shallowest and first to freeze of the five Great Lakes — could be 90 percent covered.

On Tuesday and Wednesday, the ships John J. Boland, Hon. Paul J. Martin, Indiana Harbor and James R. Barker to become stuck in ice.

The John J. Boland first became stuck in ice in western Lake Erie late Monday, and was broken out of the ice by the Morro Bay at approximately 8:45 a.m. Wednesday, the Coast Guard said.

The Indiana Harbor was beset by ice in the Middle Channel of the St. Clair River on Tuesday, and was  broken out by the Neah Bay.

The Hon. Paul J. Martin became beset by ice in western Lake Erie Tuesday, and was broken out by the Morro Bay.

The James R. Barker was first beset by ice in western Lake Erie and broken out by the tug Calusa Coast on Tuesday, but it subsequently became beset again and was freed of the ice by the Morro Bay.

The work is part of the Coast Guard’s Operation Coal Shovel, which keeps Lake Erie,  southern Lake Huron, Lake St. Clair, the St. Clair/Detroit River system, Lake Ontario and the St. Lawrence Seaway clear. The work is coordinated out of Coast Guard Sector Detroit.

The Coast Guard also breaks ice for search and rescue missions, emergency operations and flood mitigation.