Using those tips, along with reports from the Duluth Police Department, the DNT was able to deduce the pillar fell on February 7 sometime between 4:40 p.m. and 5:30 p.m.
Nearby resident Kinnan Stauber told City Pages she heard the lake "groaning" while out for a walk north of the Icehouse on February 6.
"You could hear the water rising and falling under the ice," she says. Wind along the lake picked up to 40 mph later that night and into the next day.
Andrea Woyt of Duluth sent the DNT a photo showing the pillar still standing at 4:40 p.m. on February 7. Nick Stone, a St. Paul resident, ventured out into the blustery conditions with some friends shortly after that to explore the Canal Park shoreline. They didn't realize the pillar was gone until they went back and looked at their photos.
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The photos, timestamped at about 5:30 p.m., show the pillar is gone. The ice around where it had been, which was relatively smooth in photos from that morning, is jumbled. There's no obvious patch of open water, aside from the water ponded near the icehouse that probably welled up when the column fell in. It appears that the top-heavy pillar probably was shaken loose from its wood pilings by wind and ice, and settled gently into the 12- to 14-foot depths. Chunks of ice most likely quickly covered the spot, and appear to have started to freeze back together by the time Stone and his friends arrived.
Stauber, who lives on the lake, was not surprised the pillar slipped into the lake unnoticed.
"The lake makes a lot of noise, and you might never hear a lot of things," she says. "That there was no trace mean it just froze over that quickly."
Send news tips to Ben Johnson.