St. Anthony Falls retreated roughly ten miles in twelve thousand years. However, the falls began to retreat much faster as humans built mills around it. By the 1860s, the falls had reached the tip of the Platteville formation. In 1868, a tunnel built beneath he falls collapsed, nearly destroying the entire milling industry. Turning to Congress for help, the citizens of Minneapolis and St. Anthony asked for funds to fix the falls. Congress agreed and gave the Army Corps of Engineers fifty thousand dollars to preserve the falls for upriver navigation in 1870. The Corps built a massive wall beneath the falls and a wooden apron.
|1. The Beginning of the End|
|2. The Eastman Tunnel|
|3. The Collapse|
|4. Saving the Falls|
St. Anthony Falls retreated roughly ten miles over the past ten thousand years. However, the falls began to retreat much faster as humans built mills around it. Logs floating downstream from northern Minnesota damaged the falls as they went over it, sometimes hitting the limestone with enough force to shake the ground. Millers also damaged the falls by constructing a v-shaped dam to divert water from flowing directly over the center of it. Instead, water flowed into different millponds which then ran through canals turning waterwheels. Except for floods, no water flowed over the center of falls. During the winter, freezing temperatures would crack the limestone causing the falls to retreat faster. Even when floods occurred, they still carried the giant logs over the edge, damaging the limestone.
Recognizing that their livelihood depended on the water power produced by the falls, the Minneapolis Milling Company, which controlled waterpower for the west side mills, built a wooden incline over the falls, called an apron. This apron would have prevented logs and freezing temperature from cracking the limestone and causing further retreat. Construction began in 1866 and finished in time for an 1867 flood to destroy it. Unable to find the funds rebuild the apron, the company turned toward the public and the government. However, many politicians and citizens were uneasy about providing money to repair the falls since it benefited private corporations and not the public. The company had to wait until the summer of 1869 before it finally received funding to rebuild the falls. Work went quickly until another flood delayed completion of the apron until October. Then catastrophe struck.
Workers build an apron at the falls. Image from Minnesota Historical Society. (Photographer: Beal's Art Gallery, ca. 1870)
The story of the Eastman Tunnel begins in 1865 when William Eastman, a Minneapolis lumberman, and John Merriam, a St. Paul banker, sued the East St. Anthony Company over who controlled water rights to Nicollet Island. After buying Nicollet Island from the government, Franklin Steele, the founder of the company, had lost it after mortgaging it to a fur trader named Hercules Dousman. However, in the mortgage, he did not make clear who controlled the water flowing by the island. According to the legal doctrine of riparian rights, whoever owned land next to a body of water could use the water for anything they wanted. When Dousman sold the island to Eastman and Merriam, the issue remained unresolved. 
Due to financial troubles, the company settled out of court. It agreed to share water rights with Eastman and Merriam. Furthermore, the settlement allowed Eastman and Merriam to build a tunnel underneath the Platteville from the head of Nicollet Island to the foot of Hennepin Island. The tunnel would have allowed water to flow underneath the island mills, increasing the speed of the water and the power it provided.
In 1868, workers began construction on the tunnel and on October 4, 1869, they had tunneled over two thousand feet. Five hundred feet lay ahead of them when they discovered water oozing through cracks in the limestone. The workers, unalarmed since water frequently dripped from the tunnel, finished the shift and left that night.
Soon after the workers left, the Mississippi burst through the limestone roof. Within hours, a six foot square tunnel had become a cavern ninety feet wide and sixteen and a half feet deep. Sometime in the morning of October 5, much of the Platteville formation collapsed, forming a whirlpool.
The cry for help went out and one witness recalled that “bakers deserted their ovens, lumbermen were ordered from their mills, barbers left their customers unshorn; mechanics dropped their tools; lawyers shut up their book or stopped pleading in the courts; physicians abandoned their offices.” Working together, these men constructed a huge raft, floated it over the whirlpool, and filled it with rocks and dirt to sink it into the top of the tunnel. It plugged the hole, but another whirlpool soon appeared beside the raft. After repeating the same process, they succeeded in plugging both holes. By the end of the day they inspected their work and celebrated “the triumph of human skill and brain power over the dumb force of nature.”
However, nature was not finished. As the men inspected their work on the rafts, a great suction pulled the rafts under the river and shot them back up. The men who were on the rafts managed to jump free before the rafts plunged out of sight as a hole in the river floor swallowed them. Left with no other choice, the workmen abandoned working the mills and tried to construct dams upriver to prevent its flow from entering the tunnel. 
A portion of the Eastman Tunnel collapse showing the East Side Platform Sawmills and Hennepin Island in the background. Image from Minnesota Historical Society ca. 1869.
Turning to Congress for help, the citizens of Minneapolis and St. Anthony asked for funds to fix the falls. Congress agreed and gave the Army Corps of Engineers fifty thousand dollars to preserve the falls for upriver navigation in 1870. The Corps at first tried to fill in the tunnel with concrete, but the Mississippi kept on finding new ways around the barriers they constructed. By 1874, the Corps realized that saving the falls would require much more than plugging holes.
That same year, the Corps began construction on a massive wall beneath the falls. Digging underneath the falls, they built a thirty nine foot wall beneath the Platteville formation. By the time they finished, the wall extended 1,850 feet across the face of the falls. This would prevent water from undercutting the Platteville formation and thus prevent the falls from retreating farther.
The Corps also completed the wooden apron, constructed two low dams above the falls to ensure water always flowed over the lip of the falls, and built a sluiceway, or a channel, by the waterfall to direct logs away from going over its edge. Finally, they filled the Eastman tunnel and cavern with gravel. By 1880, more than a decade after the tunnel had collapsed, the Corps finished. 
With the construction of the apron and wall, the future of the falls was insured. However, the natural beauty of the falls was lost forever. Human intervention had saved the falls but it had also destroyed it. The catastrophe of the Eastman tunnel and the heroic efforts to save it speak to the impact humans have on their environment and the effort humans must expend to prevent its destruction.
Two photos showing the completed apron at the falls. People would buy these pictures, place them on a stereopticon (which resembles a board with a frame at one end and a pair of lenses at the other), look through the lens, and see a three dimensional image. Image from the Minnesota Historical Society. (Photographer: Charles A. Tenney, 1884)
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1. Lucile M. Kane, The Falls of St. Anthony: The Waterfall that Built Minneapolis (St. Paul: Minnesota Historical Society Press, 1987), p. 63
2. Kane, The Falls, p. 63-69
3. Kane, The Falls, p. 69-70
4. Kane, The Falls, p. 70
5. Kane, The Falls, p. 71
6. John O. Anfinson, River of History: A Historic Resources Study of the Mississippi National River and Recreation Area (St. Paul: Army Corps of Engineers, 2003), p. 127
7. Anfinson, River, p. 128
8. Kane, The Falls, p. 72
9. Anfinson, River, p. 128
10. Anfinson, River, p. 128-129