Welcome to the Wannaskan Almanac for Friday.
On this day in 1869, a 2,500 foot tunnel under Hennepin Island in the Mississippi River in St. Anthony, Minnesota collapsed. The city of St Anthony was located on the east bank of the river across from Minneapolis (the two cities merged in 1872).
Both cities were booming on flour and lumber mills. The mills used water power from St Anthony Falls. This industry had narrowed the river causing the limestone cap over the falls to erode. For 10,000 years, the falls had been eroding naturally, working their way upstream at a rate of four feet per year. Thanks to development, the rate had increased to 26 feet per.
The idea of the tunnel under the river was to protect the falls while delivering the power of the river to the mills downstream. Unfortunately, the roof of the tunnel collapsed. A good chunk of Hennepin Island collapsed and a powerful stream of water began scouring the falls. If this kept up, the falls would have been reduced to a series of rapids. Minneapolis would have have become a mere suburb of Saint Paul.
Men forced whole trees into the tunnel to plug it, but the river washed them away. Dams were built to divert the river away from the tunnel but these washed away in the spring floods. Finally a wooden apron was built over the falls to protect them. Meanwhile more of Hennepin Island washed away and a couple of mills were undercut by the stream and both tumbled into the river.
A permanent fix was needed, but the citizens did not want to be taxed for the benefit of the mill owners. Finally the Army Corps of Engineers agreed to use federal money to stabilize the falls with an underground concrete dike. Their pretext was "the protection of navigation." The job was done for under a million dollars with local taxpayers kicking in about a third of the cost. Since 1876, the falls have not moved an inch.
Before Europeans arrived in 1680, the Indians had the place to themselves. They fished, hunted, and tapped the sugar maples on the islands. To the Dakota Indians, the falls were sacred. They associated the falls with Oanktehi, god of waters and evil. There was a legend of a woman who went over the falls because she was distraught that her husband had taken a second wife.
It seems troubles never end. In 2015, the government had to close the locks around the falls to prevent two invasive species of Asian carp from traveling upriver and into the 10,000 lakes. The city is trying to turn the land around Saint Anthony Falls into a recreation area. But the falls will never return to their pristine beauty, which early explorers said was equal to Niagara's.