For generations, weekend hikers trekked into C.R. Magney State Park near Grand Marais, Minnesota, to see a genuine mystery. Upon the rocks of a waterfall along the Brule River, the river splits. Most flows down the falls, but another stream swirls into a cavern called the Devil’s Kettle.
Where this second stream of water ended up, no one knew. Obviously, it had to flow somewhere. Objects thrown into the kettle failed to show up in the river or Lake Superior. Hydrologists were stumped … until now.
Cheri Zeppelin with the Minnesota Department of Natural Resources writes about an amazing discovery regarding the Devil’s Kettle in a recent edition of Minnesota Conservation Volunteer.
Without seeing an obvious resurgence of water, many people have speculated that the water followed an alternate underground path to Lake Superior. Geologists said that wasn’t likely. Underground waterways form in softer rock such as limestone, but the geology of the North Shore is anything but soft. Tunnels, or lava tubes, do not form in rhyolite or in the volcanic basalt far beneath the riverbed.
DNR springshed mapping hydrologist Jeff Green and other scientists have long thought that the water that enters Devil’s Kettle didn’t divert through a hidden channel to the lake, but rather resurfaced in the river downstream. To test this theory, Green asked the DNR’s water monitoring and surveys unit to measure the volume of water flowing above and below Devil’s Kettle using stream gauging equipment. By comparing the amount of water flowing above the waterfall with the amount of water flowing below the falls, hydrologists could determine if there was a loss of water somewhere between the locations.
In late fall 2016, hydrologists Heather Emerson and Jon Libbey measured water flow above Devil’s Kettle at 123 cubic feet per second. Several hundred feet below the waterfall, the water was flowing at 121 cubic feet per second. “In the world of stream gauging, those two numbers are essentially the same and are within the tolerances of the equipment,” Green explains. “The readings show no loss of water below the kettle, so it confirms the water is resurging in the stream below it.”
The mystery of the Devil’s Kettle is that the water flows to its destiny regardless.
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My Great Northern Radio Show travelled to Grand Marais for a show in June 2015. I wrote a sketch speculating about the possible destination of the Devil’s Kettle water back then that you might enjoy today.
The Great Northern Radio Show broadcasts from the Chief Theater in downtown Bemidji this Saturday, March 4. Join us or tune in!