Saint Anthony Falls
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Saint Anthony Falls, or the Falls of Saint Anthony, located near downtown Minneapolis, Minnesota, was the only waterfall on the Upper Mississippi River until it was replaced by a concrete apron after they partially collapsed in 1869 and, later, a series of dams in the 1950s and 1960s. The indigenous people who lived in their vicinity called the falls by various names. The Ojibwe term was Kakabikah (Gakaabikaa, "waterfall over a cliff")[1] and the Dakota used Minirara (curling water) and Owahmenah (falling water).[1] In 1680, the falls became known to the rest of the world when they were observed by Father Louis Hennepin, a Catholic friar of Belgian birth,[2] who also brought the existence of Niagara Falls to the world's attention. Hennepin named Saint Anthony Falls after his patron saint, Anthony of Padua.[3] Later explorers include Jonathan Carver and Zebulon Montgomery Pike. The region around the falls was added to the National Register of Historic Places as the Saint Anthony Falls Historic District in 1971.
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[edit] Geology
Geologists say that the falls first appeared roughly 10,000 years ago several miles downstream near the confluence of the Minnesota River, around modern-day Saint Paul.[4] Estimates are that the falls were about 180 feet high at that time. The massive River Warren, a precursor of today's Minnesota River, had a waterfall that is said to have been twice as wide as Niagara Falls. Over the millennia, the falls moved upstream, breaking off into several smaller waterfalls as tributaries were reached. Minnehaha Falls in south Minneapolis is one of several such examples.
From its origins near Fort Snelling, St. Anthony Falls relocated upstream at a rate of about 4 feet per year until it reached its present location in the early 1800s. When Father Louis Hennepin documented the falls he estimated the falls' height to be 50 or 60 feet. Later explorers described it as being in the range of 16 to 20 feet high.[5]
As Minneapolis (and its former neighbor across the river, St. Anthony) developed, the water power at the falls became a source of power for several industries. Water power was used by sawmills, textile mills, and flour mills. Millers on the Minneapolis side extracted power by diverting upper-level water into waterwheel-equipped vertical shafts (driven through the limestone bedrock into the soft, underlying sandstone) and then through horizontal tunnels to the falls' lower level. These shafts and tunnels weakened the limestone and its sandstone foundation, accelerating the falls' upriver erosion to 26 feet per year between 1857 and 1868. The falls quickly approached the edge of their limestone cap; once the limestone had completely eroded away, the falls would degenerate into sandstone rapids unsuitable for waterpower.[6]
In 1868, the falls were in danger of collapse due to the weakness of the underlying structure. The limestone ledge that underlaid the falls was further damaged by runaway logs from upstream logging operations and by freeze-thaw cycles exacerbated by the millers' water diversions. A mill tunnel, under construction by William Eastman and John Merriam, collapsed, creating a whirlpool that caused the downriver tip of nearby Nicollet Island to quickly erode. During the spring of 1870, flood water and debris caused the limestone cap to collapse, and several mills and other buildings fell into the river.[7]
To protect the falls, hundreds of volunteers worked swiftly to build a series of dams that would prevent further collapse of the falls. The United States government also assisted in shoring up the falls, in an effort to preserve navigation on the river. By 1884, an apron was completed, the tunnel was sealed, and a dike protected the sandstone from water seepage. The United States government spent $615,000 on this effort, with an additional expense of $334,500 borne by Minneapolis and St. Anthony. [2]
St. Anthony Falls was the upper limit of commercial navigation on the Mississippi until two dams and a series of locks were built between 1948 and 1963 by the United States Army Corps of Engineers. The locks make commercial navigation possible above Minneapolis but, since the locks in Minneapolis are smaller than most of the locks on the river, the practical limit for many commercial tows is farther downriver. Few barges go past St. Paul.
[edit] Locks and dams
Completed in 1963, the upper St. Anthony Falls dam is a horseshoe-shaped hydro-electric dam 93 feet (28 m) in height. The upper pool has a normal capacity of 3,150 acre feet (3,885,000 m³) and a normal level of 799 feet (244 m) above sea level. The navigation channel required alteration of the historic Stone Arch Bridge, which now has a metal truss section to allow ships to pass below.
Completed in 1956, the lower St. Anthony Falls dam is a gravity-type hydro-electric dam 60 feet (18 m) in height, consisting of a 275 foot (84 m) long concrete spillway with 4 tainter gates. The lower pool (sometimes called the intermediate pool) has a normal capacity of 375 acre-feet (463,000 m³) and a normal level of 750 feet (229 m) above sea level.
The pool below the lower dam has a normal level of 725 feet (221 m) above sea level.
The upper and lower locks are each 56 feet (17 m) wide by 400 feet (122 m) long.
Even though the falls often don't look very dangerous, the current is swift and people sometimes find themselves very bad situations in the area. In 1991, a small boat drifted too close and fell over one part of the dam. Two people onboard were killed, and two others had to be rescued by helicopter. Rescues at the site are usually much less dramatic, but continue to happen occasionally.
Jesse Ventura's brother Jan Janos has been a dam operator at the site for many years.
[edit] See also
- Saint Anthony Main - adjacent shopping area.
[edit] References
- ^ Freelang Ojibwe Dictionary. Retrieved on 2007-03-11.
- ^ Pennefeather, Shannon M. (2003). Mill City: A Visual History of the Minneapolis Mill District. St. Paul, Minnesota: Minnesota Historical Society.
[edit] External links
- U.S. Army Corps of Engineers St. Paul District: Upper St. Anthony Falls
- U.S. Army Corps of Engineers St. Paul District: Lower St. Anthony Falls
- Engineering the Falls: The Corps Role at St. Anthony Falls - an article on the U.S. Army Corps of Engineers website covering the history and geology of St. Anthony Falls.
| Locks and dams of the Upper Mississippi River | |
|---|---|
| USAF | LSAF | 1 | 2 | 3 | 4 | 5 | 5A | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 24 | 25 | 26 | 27 | |
| Upstream: — |
Downstream: Meeker Island Lock and Dam (demolished) |
