Lake Superior shipping season ends tonight

The 2013 shipping season on the Lake Superior ends at midnight Wednesday with the closing of the Soo Locks at the eastern end of Lake Superior.

Thick ice was a challenge for ships this winter. Icebreakers in the Duluth harbor had to cut through two-foot thick ice starting in mid-December to keep shipping channels clear. Ice clogged the rivers connecting the Great Lakes.

Ten Great Lakes freighters will winter in the Duluth-Superior harbor this year. The vessels typically require up to $1 million in repairs and maintenance, including draining water and inspecting equipment.

"Vessels are operational for very long lives on the Great Lakes because of the fresh water, but that doesn't relieve you from having to keep them maintained," said Jim Sharrow, facilities manager with the Duluth Seaway Port Authority. "This is a perfect time do it when they're not operating."

The Soo Locks will reopen on March 25.