Devil's Kettle: The Minnesota Waterfall That Seems to Vanish

The Brule River runs out of the woods of northeastern Minnesota and down toward Lake Superior, dropping about 800 feet over its last 8 miles inside Judge C.R. Magney State Park. Along the way, it pours over a series of waterfalls. At one of them, a large rock splits the river in two. On the east side, the water tumbles about 50 feet into a pool and keeps flowing toward Lake Superior. On the west side, it pours into a deep pothole in the volcanic rock, and seems to vanish. That hole is the Devil's Kettle, and for decades it was one of Minnesota's best-known mysteries. Where did the water go? People tossed in sticks, logs and ping-pong balls, hoping to see them pop up downstream. They never did. A popular theory held that the water traveled through some underground passage all the way to Lake Superior. In the fall of 2016, the Minnesota Department of Natural Resources tried a different approach. Instead of chasing objects, its hydrologists measured the water itself. Using stream gauges, they found the river flowing at 123 cubic feet per second above the Devil's Kettle and 121 cubic feet per second a few hundred feet below it. In stream gauging, those numbers are essentially the same, within the equipment's margin of error. The river hadn't lost any water. The DNR announced the results in February 2017: the water going into the kettle rejoins the Brule River just below the falls. So why don't the logs and ping-pong balls come back? DNR hydrologist Jeff Green explained that the plunge pool below the kettle is a powerful system of recirculating currents. It can trap objects underwater, thrash them around and break them up before they resurface somewhere downstream. The hydrologists planned a final confirmation: a fluorescent, biodegradable dye poured into the kettle at low water, to show exactly where the water comes back up. That dye trace was not completed. The flow measurements, though, settled the main question. Today, the Devil's Kettle Trail is one of the most popular hikes in Minnesota. In a USA Today 10Best readers' poll, it was voted the best hiking trail in the country. Visitors still stand at the edge of the gorge and watch half a river pour into a hole, now knowing the water is just a short distance away, coming back up into the Brule.