BLACK HOLE MYSTERY DEEPENS
Why did it freeze over just when weather was getting warmer?
True to its nature, the black hole on North Long Lake has suddenly and mysteriously changed.
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After staying open for several weeks, the hole froze over Tuesday night during some of the warmest January weather on record. Why it froze at this time is the latest unanswerable question about the hole, which first appeared in February 2002 and has defied explanation.
"It's been cold enough to freeze at night," said Al Cibuzar of A.W. Research in Brainerd, the company hired to study the hole. "But what was going on there before in regard to thermal imaging doesn't seem to be going on anymore. The upwelling isn't as extensive."
Thermal images of the hole taken Tuesday showed two spots where the water was warmer than the rest, Cibuzar said. But the cause remains a mystery.
"We're seeing some of the same unusual things we saw last spring," Cibuzar said. "But we must go through the data before we say what they are. By early next week we should have some results."
Todd Matthies, a member of the Minnesota School of Diving, approached a small hole in the ice on the Highway 371 bay of North Long Lake Wednesday. Matthies was the first of four divers to investigate a 2,000-foot by 400-foot hole in the ice that first appeared in February 2002. (Dispatch Photo by Clint Wood)
Divers entered the hole Wednesday through a small channel that remained open, although in one place a layer of ice was found beneath the surface layer of ice and that second layer had to be opened with a chisel.
Todd Matthies, Tim Moe and Pat Krueger, all of the Minnesota School of Diving in Brainerd, videotaped and photographed the bottom of the lake under the hole, which measures about 2,000 feet long by 400 feet wide on the Highway 371 bay.
"Saw a few fish, some snails, weeds, pretty typical stuff so far," said Matthies, the first diver to investigate the hole.
Matthies put a dye in the water that enables a camera to detect currents flowing through the hole.
"It didn't seem to move much," Matthies said of the dye. "But it's hard for me to determine that. We need to analyze the film."
The other divers measured water temperature, dissolved oxygen, pH content and conductivity.
Wednesday's operation was observed by a dozen lake residents, as well as area and Twin Cities media. Coffee and doughnuts were served at the lake access by the Thirty Lakes Watershed District.
The Crow Wing County Sheriff's Department had a Hovercraft on hand for emergency rescue. But the only rescue it made was of a portable fish house that had been set up as a warming house for the divers. A gust of wind caught the house and blew it onto the black hole.
But the thin layer of ice covering the hole prevented the fish house from becoming the hole's 13th casualty.