Hennepin Island tunnel
Encyclopedia
Minneapolis, Minnesota
Minneapolis , nicknamed "City of Lakes" and the "Mill City," is the county seat of Hennepin County, the largest city in the U.S. state of Minnesota, and the 48th largest in the United States...
) dug beneath the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
riverbed between 1868 and 1869 to create a downstream spillway
Spillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...
for hydro plants, milling and lumber business located upstream of St. Anthony Falls. The tunnel ran downstream from Nicollet Island
Nicollet Island
Nicollet Island is an island in the Mississippi River just north of downtown Minneapolis, Minnesota, named for cartographer, Joseph Nicollet. DeLaSalle High School and the Nicollet Island Inn are located there, as well as three multi-family residential buildings and twenty-two restored...
, beneath Hennepin Island, and exited below St. Anthony Falls.
During construction of the tunnel, on October 5, 1869, the river broke through the thin layer of limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
separating the river's bed from the tunnel. The rushing river scoured the tunnel, caving in parts of Hennepin Island and causing the earth supporting St. Anthony Falls to collapse upstream. There was serious concern that the riverbed would crumble and reduce St. Anthony Falls to a long set of rapids. However, within a few weeks, dams were built to divert the river and stop St. Anthony Falls from being washed away. The fix was temporary as the 1870 spring floods damaged some of the new dams and swept away more of Hennepin Island. By the fall of 1870, the riverbed and banks were stabilized and a wooden apron capped St. Anthony Falls to stop the upstream progression of the collapsing falls. As a direct result of the collapse of the Hennepin Island tunnel, St. Anthony Falls ultimately received a sloping concrete apron to create an artificial falls that are held out as the only major waterfall on the Mississippi River.
The site of the tunnel is about a mile upstream from the 2007 collapse of the I-35W Mississippi River bridge.
History
Hennepin Island was named after explorer, Catholic priest, and FranciscanFranciscan
Most Franciscans are members of Roman Catholic religious orders founded by Saint Francis of Assisi. Besides Roman Catholic communities, there are also Old Catholic, Anglican, Lutheran, ecumenical and Non-denominational Franciscan communities....
missionary
Missionary
A missionary is a member of a religious group sent into an area to do evangelism or ministries of service, such as education, literacy, social justice, health care and economic development. The word "mission" originates from 1598 when the Jesuits sent members abroad, derived from the Latin...
Louis Hennepin (12 May 1626 – c.
Circa
Circa , usually abbreviated c. or ca. , means "approximately" in the English language, usually referring to a date...
1705). In 1865, entrepreneurs William W. Eastman and John L. Merriam had bought its sister island, Nicollet Island, with the idea of creating a tunnel from Nicollet Island under St. Anthony Falls to provide for-profit spillway services to the many milling and lumber business located upstream of St. Anthony Falls. The tunnel was to be part of a system of waterworks that supported the industries driving Minneapolis' growth. The project was designed to create more industry on Nicollet Island through the waterpower.
St. Anthony Falls are made up of a hard limestone cap over soft sandstone. 10,000 years ago the falls were located near present-day Fort Snelling, Minnesota
Fort Snelling, Minnesota
Fort Snelling, originally known as Fort Saint Anthony, was a military fortification located at the confluence of the Minnesota River and Mississippi River in Hennepin County, Minnesota...
at the mouth of the glacial River Warren
Glacial River Warren
right|thumb|210px|The course of the Minnesota River follows the valley carved by Glacial River WarrenGlacial River Warren or River Warren was a prehistoric river that drained Lake Agassiz in central North America between 11,700 and 9,400 years ago...
. However, in the succeeding millennia, the river had been washing away the sandstone and undermining the limestone lip of St. Anthony Falls, causing the falls to slowly retreat upriver near its present location.
In 1868, workers began to dig a 2500 feet (762 m)-long tunnel beneath the riverbed from Nicollet Island downstream under Hennepin Island, exiting below the falls. For the next year, workers dug in the soft sandstone beneath the thin layer of limestone that forms the river's bed. However, by October 1869, water began seeping into the tunnel from above.
"Proprietors of stores hastened to the falls, taking their clerks with them; bakers deserted their ovens, lumbermen were ordered from the mills, barbers left their customers unshorn; mechanics dropped their tools; lawyers shut up their books or stopped pleading in the courts; physicians abandoned their offices. Through the streets, hurrying hundreds were seen on their way to the falls."
Work started immediately to plug the tunnel and hundreds of volunteers used timbers and stones. However, the river easily washed these out of the tunnel. Within a few weeks, the plug held and dams were built to divert the river and stop St. Anthony Falls from being washed away. The fix was temporary and the 1870 spring floods tore up some of the new dams and swept away more of Hennepin Island. In addition, the earth support below the Summit flour mill, Moulton's planing mill
Planing mill
A planing mill is a facility that takes cut and seasoned boards from a sawmill and turns them into finished dimensional lumber. Machines used in the mill include the planer and matcher, the molding machines, and varieties of saws...
and a wheat storehouse were undermined and each of these was tipped into the river.
By the fall of 1870, the riverbed and banks were stabilized and a wooden apron capped St. Anthony Falls to stop the upstream progression of the collapsing falls. The apron buried the falls' jagged rocks and large waterfall cataract and tamed the falls' tumbling water.
Aftermath
The tremendous damage caused by the Hennepin Island tunnel brought lawsuits and demands for political change. A central issue at that time was whether local taxpayers should pay for repairs that would enrich riverfront industrialists. The tunnel collapse was one of the factors leading to the merger of St. Anthony with Minneapolis in 1872. To the relief of the local population, the United States Army Corps of EngineersUnited States Army Corps of Engineers
The United States Army Corps of Engineers is a federal agency and a major Army command made up of some 38,000 civilian and military personnel, making it the world's largest public engineering, design and construction management agency...
made the repairs using federal money on the pretext that it was protecting navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
. Seven years after the tunnel collapse, by 1876, the falls were stabilized with an underground dike and low dams that largely are still in place upstream of Stone Arch Bridge. By 1880, the Army Corps of Engineers had covered the face with a sloping concrete apron, creating the artificial falls. The federal government spent $615,000 on this effort, while the two cities (St. Anthony and Minneapolis) spent $334,500.
See also
- Hennepin Avenue BridgeHennepin Avenue BridgeThe Hennepin Avenue Bridge is the structure that carries Hennepin County State Aid Highway 52, Hennepin Avenue, across the Mississippi River in Minneapolis, Minnesota at Nicollet Island. Officially, it is the Father Louis Hennepin Bridge, in honor of the 17th-century explorer Louis Hennepin, who...
- Hennepin AvenueHennepin AvenueHennepin Avenue is a major street in Minneapolis, Minnesota, United States. It runs from Lakewood Cemetery , north through the Uptown District of Southwest Minneapolis, through the former "Bottleneck" area west of Loring Park, through the North Loop in the city center, to Northeast Minneapolis and...
- Hennepin Island Hydroelectric PlantHennepin Island Hydroelectric PlantThe Hennepin Island Hydroelectric Plant also known as the St. Anthony Hydro Plant, sits on the site of early sawmills at St. Anthony Falls in Minneapolis, Minnesota. The current structure was built for electric power in 1882. It is currently operated by Xcel Energy...
- History of Minneapolis, MinnesotaHistory of Minneapolis, MinnesotaMinneapolis is the largest city in the state of Minnesota in the United States, and the county seat of Hennepin County. The origin and growth of the city was spurred by the proximity of Fort Snelling, the first major United States military presence in the area, and by its location on Saint Anthony...
- Louis HennepinLouis HennepinFather Louis Hennepin, O.F.M. baptized Antoine, was a Catholic priest and missionary of the Franciscan Recollect order and an explorer of the interior of North America....
- Mill Ruins ParkMill Ruins ParkMill Ruins Park is a park in downtown Minneapolis, Minnesota, United States, standing on the west side of Saint Anthony Falls on the Mississippi River. The park interprets the history of flour milling in Minneapolis and shows the ruins of several flour mills that were abandoned.The park is the...
- Mills District, MinneapolisMills District, MinneapolisThe Mill District is a neighborhood within Minneapolis, Minnesota, United States, and a part of the larger Downtown East neighborhood. Its approximate boundaries are the Mississippi River to the north, the I-35W Mississippi River Bridge to the east, Washington Avenue to the south, and 5th Avenue...
- North Star Woolen MillNorth Star Woolen MillThe North Star Woolen Mill is a building in downtown Minneapolis, Minnesota. The building, located in the St. Anthony Falls Historic District, was originally a textile mill for the North Star Woolen Company. The mill was built in 1864 by W.W. Eastman and Paris Gibson on the west side of the west...
- Northwestern Consolidated Milling CompanyNorthwestern Consolidated Milling CompanyNorthwestern Consolidated Milling Company was an American flour milling company that operated about one quarter of the mills in Minneapolis, Minnesota when the city was the flour milling capital of the world. Formed as a business entity, Northwestern produced flour for the half century between 1891...
- Pillsbury "A" Mill
- Washburn "A" Mill
- I-35W Mississippi River bridge