Marine group wants super lock built at Sault.

A broken navigational lock on the American side of the St. Mary's River at Sault Ste. Marie, Mich, cost Great Lakes shippers a quarter-million dollars over the summer, said a marine industry group.

The 20-day closure of die MacArthur Lock cost U.S.-flagged vessel operators nearly $250,000 in delays.

The U.S. Army Corps of Engineers said a misalignment of the miter gates forced the closure of the lock on July 29. It was back open to service on August 17.

During that period, the Lake Carriers Association said American "lakers" carrying more than 1.8 million tons were delayed 77 times for a total of 6.5 days.

The temporary shutdown of the lock feeds the Lake Carriers' Association lobbying efforts for a second super-sized lock to be built at the Sault. The Poe Lock is the largest in the St. Lawrence Seaway System, built to handle the biggest ships.

"The lengthy failure of the MacArthur Lock adds more urgency to our efforts to build a second Poe-sized lock," said association president James H.I. Weakley in a news release. "The MacArthur Lock is 72 years old and the Poe Lock is 46 years old. We must renew this vital infrastructure. Most of the iron ore that feeds our steel mills...