The Mystery of Devil’s Kettle Solved?
GRAND MARAIS, Minn. – Devil’s Kettle waterfall on the Brule River, at Judge C.R. Magney State Park near Grand Marais, has baffled scientists and enchanted onlookers for years. The waterfall plunges into a cavernous hole in the rock and simply seems to vanish, which has left many wondering where does all the water go?
Many onlookers, out of sheer curiosity, would toss a stick or other buoyant item into the water and see if it would resurface downstream, but nothing ever did. It was speculated that the water traveled underground directly to Lake Superior, but geologists quickly dismissed this hypothesis. Due to the type of rock found in the area, it was highly unlikely.
In the fall of 2016, hydrologists from the Minnesota Department of Natural Resources tested their theory that the water didn’t divert into an underground channel to the lake, but rather it simply resurfaced downstream. In order to test this, they conducted water monitoring tests, which would measure the volume of water flowing above and below Devil’s Kettle using stream gauging equipment.
Their results yielded nearly identical volumes of water flowing above and below the waterfall. Above, stream gauges measured the flow of the Brule River at 123 cubic feet per second, and below, gauges detected 121 feet per second.
“In the world of stream gauging, those two numbers are essentially the same and are within the tolerances of the equipment,” explained DNR springshed mapping hydrologist Jeff Green. “The readings show no loss of water below the kettle, so it confirms the water is resurging in the stream below it.”
Green and Calvin Alexander, a colleague at the University of Minnesota, plan to conduct a dye trace to show where the water resurfaces. In the fall of 2017, during low-water flow, they will pour a fluorescent, biodegradable dye into the pothole and note where the dye re-enters the river.
As for the mystery of disappearing objects in Devil’s Kettle, water force and fluid dynamics offer an explanation. Due to forceful currents in the pothole, materials can be held beneath the water and even disintegrated because of it.