DULUTH – A former US Army Corps of Engineers tug has begun to sink in Duluth Harbour.

The private boat named Lake Superior, moored in a slipway near Pier B off Railroad Street, developed a hole in a ballast tank, said US Coast Guard Lt. Joseph McGinnis.

“It was last weekend, but the ice held it up until it started to melt,” he said.

It was not known how the hole developed. On Tuesday, the stern of the ship was submerged and the Coast Guard evacuated the water with pumps, while its maritime security unit in Duluth monitored the situation. McGinnis said Coast Guard pollution responders are ready to mitigate any environmental risk, with diesel and lube oil on board the tug. The boat is not leaking in the harbor and the vessel is in a safe place where it will not interfere with any other craft, he said.

According to its former owner, the Duluth Entertainment Convention Center (DECC), the 114-foot tug was built in San Francisco in 1943 for the United States Army and was first named Emil H. Block. As an army vessel, she worked in the South Pacific moving barges between islands in the Philippines. She sank in 1950. Repairs were made and she began work on Lake Superior for the renamed Army Corps Lake Superior, pulling the dredge barge into Duluth Harbor. He also carried out breakwater work at Two Harbors. The Corps retired the tug in 1995 and donated it to DECC.

The DECC used the ship as a museum until it was sold to Billington Contracting for $56,262 in 2007, said DECC communications director Lucie Amundsen. Efforts to reach the business owner were unsuccessful.

An old listing of the tug touted its oak and mahogany features and brass fittings.

Lake Superior would be the second tug to sink in Duluth Harbor in recent years. In 2009, the 85-foot tug Essayons sank in its hold. It belonged to Hobart Finn.