Mystery of Minnesota North Shore waterfalls may be solved
DULUTH, Minn.—A recent study of Devil's Kettle Falls on Minnesota's North Shore, completed out of "scientific curiosity," shed light on the waterfall's phenomenon, a state hydrologist said.
In Judge C.R. Magney State Park, the Brule River splits into two at Devil's Kettle, with one branch flowing over a typical waterfall and the other branch disappearing into a hole at the bottom. Using stream gauges, the Minnesota Department of Natural Resources determined that the water rejoins the river farther downstream, the agency announced on Tuesday.
"It's still a fascinating place. People should still go look at it because it's still a neat-looking phenomenon, no matter where the water is coming back up. To just watch the river go into that is just enthralling," said Jeff Green, a DNR hydrologist based in Rochester.
The idea to study Devil's Kettle has been in the back of Green's mind since visiting the waterfall on a vacation two decades ago. He conducts dye testing as part of his job and he always thought it would be fun to use dye in Devil's Kettle to trace where the water goes after it disappears into the hole, he said. His friend Calvin Alexander, a retired University of Minnesota professor who also uses dye testing, suggested they test Devil's Kettle after he also visited the waterfall a year ago. However, they decided the river's flow should be measured first to determine if the water does, in fact, vanish from the river.
Measuring the river in November, DNR hydrologists Heather Emerson and Jon Libbey found that the river flowed at 123 cubic feet per second above Devil's Kettle and was 121 cubic feet per second about 500 feet downstream from Devil's Kettle — suggesting the water flows elsewhere and then rejoins the river somewhere below the waterfall.
"Lo and behold, the numbers are the same. It's science in action," Green said.
Green and Alexander are planning this fall to pour a fluorescent, biodegradable dye into Devil's Kettle to more precisely determine where the water rejoins the river after it disappears. Green said he's heard there was a dye test and a test using ping-pong balls completed at some point, but the DNR doesn't have any record of previous tests or results and he would like to see those results if anyone has them.