Upper Mississippi River

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Upper Mississippi River
The Upper Mississippi River near Harpers Ferry, Iowa
CountryUS, Canada [1]
Physical characteristics
 • locationLake Itasca, Minnesota[1]
 • coordinates47°15′11″N 95°12′43″W / 47.253°N 95.212°W / 47.253; -95.212
 • elevation450 m (1,480 ft)[2]
 • location
St. Louis, Missouri (flows into the Middle Mississippi) [1]
Length1,300 miles (2092.147 km) [3]
Basin size490,000 km2 (190,000 sq mi)[4]
 • average5,796 m3/s (204,700 cu ft/s)[5]
Barge going under the Mississippi River Bridge (La Crosse, Wisconsin)

The Upper Mississippi River is today the portion of the Mississippi River upstream of St. Louis, Missouri, United States,[1] at the confluence of its main tributary, the Missouri River.[citation needed] Historically, it may refer to the area above the Arkansas Post, above the confluence of Ohio River, or above Cape Girardeau.


In terms of geologic and hydrographic history, the Upper Mississippi east and south of Fort Snelling is a portion of the now-extinct Glacial River Warren which carved the valley of the Minnesota River, permitting the immense Glacial Lake Agassiz to join the world's oceans at the Gulf of Mexico. The collapse of ice dams holding back Glacial Lake Duluth and Glacial Lake Grantsburg carved out the Dalles of the St. Croix River at Interstate Park. The Upper Mississippi River valley likely originated as an ice-marginal stream during the Pre-Illinoian Stage.[6][7]

The Driftless Area is a portion of North America left unglaciated at that ice age's height, hence not smoothed out or covered over by previous geological processes.

Inasmuch as the Wisconsin glaciation formed lobes that met (and blocked) where the Mississippi now flows, and given that huge amounts of glacial meltwater were flowing into the Driftless Area, and that there is no lakebed, it is assumed that there were instances of ice dams bursting.[citation needed]


The Upper Mississippi from below St. Anthony Falls (Minneapolis, Minnesota) downstream to St. Paul, Minnesota is a gorge with high limestone bluffs carved by the waterfall. Upstream of the waterfall the land slopes gently to rivers edge. Downstream of downtown St. Paul the river enters its wide preglacial valley. The states of Minnesota, Wisconsin and Iowa, along with the federal government, have preserved certain areas of the land along this reach of the river.

There are three National Park Service sites along the Upper Mississippi River. The Mississippi National River and Recreation Area is the National Park Service site dedicated to protecting and interpreting the Mississippi River itself. The other two National Park Service sites along the river are: Effigy Mounds National Monument and the Gateway Arch National Park (home to the Gateway Arch in St. Louis).

Unlike the Lower Mississippi, much of the upper river is a series of pools created by a system of 29 locks and dams. The structures were authorized by Congress in the 1930s, and most were completed by 1940.[8] A primary reason for damming the river is to facilitate barge transportation. The dams regulate water levels for the Upper River and play a major part in regulating levels on the Lower Mississippi. [citation needed]

Kings bluff to the left in the image
Upper Mississippi Valley close to Winona, Minnesota and Kings Bluff


Locks and dam 15
Lock and dam 7 with I-90 in the background

On the upper reaches near the Minnesota-Wisconsin border, the river's floodplain is between 1.5 and 5 kilometers (between 1 and 3 mi) wide. South of St. Louis, Missouri, the alluvial floodplain is approximately 80 kilometers (50 mi) wide. Major tributaries to the Upper Mississippi River include the Missouri, Illinois, Minnesota, St. Croix, Chippewa, Black, Wisconsin, and Kaskaskia Rivers.[9]

The Upper Mississippi provides habitat for more than 125 fish species and 30 species of freshwater mussels. Three national wildlife refuges along the river cover a total of 465 square kilometers (285,000 ac). The largest of them, the Upper Mississippi River National Wildlife and Fish Refuge, is over 420 kilometers (260 mi) long, reaching from the Alma, Wisconsin area down to Rock Island, Illinois. The refuge consists of blufflands, marshes, bottomland forest, islands, channels, backwater lakes and sloughs.[9][10] It is part of the Mississippi Flyway.

Although the river is much cleaner than it was in recent decades, water quality is still a priority concern. Agricultural runoff, including sediment, excessive nutrients, (particularly nitrogen and phosphorus), and chemicals from agricultural and industrial sources continue to threaten Upper Mississippi River aquatic resources. In addition new threats continue to emerge such as personal care items including pharmaceuticals and endocrine-disrupting chemicals. The five states bordering the Upper Mississippi River are working together to address water quality issues.[11][12][13]

There is general agreement that nutrients are contributing to the Gulf of Mexico dead zone and to eutrophication problems in Lake Pepin, a large natural riverine lake that is part of Pool 4 of the Upper Mississippi River. National and regional efforts are addressing these problems, but nutrient impairment problems are occurring elsewhere in the Upper Mississippi River as well, particularly in off-channel portions. Excessive nutrients contribute to thick floating mats of filamentous algae or duckweeds that have a pronounced negative impact on light penetration and may threaten the growth and persistence of submerged aquatic vegetation that is important for fish and aquatic life, including waterfowl. Efforts to control nutrients from point and non-point sources in the basin have aimed to provide additional benefits.[14][failed verification]


The inland and intracoastal waterways, with the Upper Mississippi highlighted in red.

Navigation locks allow towboats, barges, and other vessels to transit the dams. Approximately 1350 kilometers (850 mi), from the head of navigation in Mile 858, Minneapolis, Minnesota down to Cairo, has been made suitable for commercial navigation with a depth of 2.75 meters (9 ft).[9] The agriculture and barge transportation industries have lobbied in the late 20th and early 21st centuries for a multibillion-dollar project to upgrade the aging lock and dam system. Some environmental groups and advocates of budgetary restraint argue that the project lacks economic justification.[15]

Each lock and dam complex creates a pool upstream of it. There are 29 locks on the Upper Mississippi maintained by the U.S. Army Corps of Engineers—from Upper St. Anthony Falls upstream to Chain of Rocks downstream.[16] The locks provide a collective 123 meters (404 ft) of lift.[17]

La Crosse County barge harbor
Lock and Dam 6 time lapse
Barge on the Upper Mississippi

Expansion proposals for locks[edit]

Upper Mississippi locks expansion study

The Army Corps of Engineers has studied expanding locks 20, 21, 22, 24, and 25 on the Upper Mississippi.[18]

List of pools and locks[edit]

Pool Locality Lock Mile marker (km) Distance (km)
USAF Pool Minneapolis MN Upper St. Anthony Falls Lock 854 1375    
LSAF Pool Minneapolis MN Lower St. Anthony Falls Lock 853 1373 1 2
Pool 1 Minneapolis MN Lock 1 848 1365 5 8
Pool 2 Hastings MN Lock 2 815 1312 33 53
Pool 3 Welch MN Lock 3 797 1283 18 29
Pool 4 Alma WI Lock 4 753 1212 44 71
Pool 5 Minnesota City MN Lock 5 738 1188 15 24
Pool 5A Fountain City WI Lock 5A 728 1172 10 16
Pool 6 Trempealeau WI Lock 6 714 1150 14 23
Pool 7 La Crescent MN Lock 7 703 1132 11 18
Pool 8 Genoa WI Lock 8 679 1093 24 39
Pool 9 Eastman WI Lock 9 648 1043 31 50
Pool 10 Guttenberg IA Lock 10 615 990 33 53
Pool 11 Dubuque IA Lock 11 583 939 32 52
Pool 12 Bellevue IA Lock 12 557 897 26 42
Pool 13 Clinton IA Lock 13 522 840 35 56
Pool 14 LeClaire IA Lock 14 493 794 29 47
Pool 15 Rock Island IL Lock 15 483 778 10 16
Pool 16 Illinois City IL Lock 16 457 736 26 42
Pool 17 New Boston IL Lock 17 437 704 20 32
Pool 18 Gladstone IL Lock 18 410 660 27 43
Pool 19 Keokuk IA Lock 19 364 586 46 74
Pool 20 Canton MO Lock 20 343 552 21 34
Pool 21 Quincy IL Lock 21 325 523 18 29
Pool 22 New London MO Lock 22 301 485 24 39
Pool 24 Clarksville MO Lock 24 273 440 28 45
Pool 25 Winfield MO Lock 25 241 388 32 52
Mel Price Pool East Alton IL Melvin Price Lock 201 324 40 64
Pool 27 Granite City IL Lock 27 185 298 16 26

See also[edit]


  1. ^ a b c d "Mississippi River | History, Physical Features, Culture, & Facts". Encyclopedia Britannica. Retrieved 2020-06-03.
  2. ^ "General Information about the Mississippi River". U.S. National Park Service. Retrieved 2006-04-01.
  3. ^ "UMESC - About the Upper Mississippi River System". www.umesc.usgs.gov. Retrieved 4 June 2020.
  4. ^ "River and Basin Facts". Upper Mississippi River Basin Association. Retrieved 2009-04-07.
  5. ^ "Background on Upper Mississippi River Basin". EPA: Mississippi River Basin & Gulf of Mexico Hypoxia. Retrieved 2006-04-01.
  6. ^ Hallberg, G. R. (1986). "Pre-Wisconsin glacial stratigraphy of the central plains region in Iowa, Nebraska, Kansas, and Missouri". Quaternary Science Reviews. 5: 11–15. Bibcode:1986QSRv....5...11H. doi:10.1016/0277-3791(86)90169-1.
  7. ^ Richmond, G. (1986). "Summation of quaternary glaciations in the United States of America". Quaternary Science Reviews. 5: 183–196. Bibcode:1986QSRv....5..183R. doi:10.1016/0277-3791(86)90184-8.
  8. ^ "About the Upper Mississippi River System". USGS Upper Midwest Environmental Sciences Center. Retrieved 2006-03-13.
  9. ^ a b c "Basin Facts". Upper Mississippi River Basin Association. Retrieved 2006-04-01.
  10. ^ "About the refuges". Friends of the Upper Mississippi River Refuges. Archived from the original on April 3, 2005. Retrieved 2006-04-01.
  11. ^ "Issues and Challenges- Water Quality". Upper Mississippi River Conservation Committee. Archived from the original on 2007-10-15. Retrieved 2008-04-11.
  12. ^ "2007 Water Quality Program Report- Protecting Water Quality through Interstate Cooperation". Upper Mississippi River Basin Association. Retrieved 2008-04-11.
  13. ^ "Upper Mississippi River Nutrient Monitoring, Occurrence, and Local Impacts: A Clean Water Act Perspective" (PDF). Upper Mississippi River Basin Association. Retrieved 2012-03-21.
  14. ^ "Nutrient Impairment Identification in the Upper Mississippi River". Mississippi River Basin Nutrients Science Workshop, October 4–6, 2005. Archived from the original on 2008-01-17. Retrieved 2008-04-11.
  15. ^ Marcia Zarley Taylor (8 March 2006). "River debate continues". AgWeb. Retrieved 2006-03-13.[dead link]
  16. ^ There is a Lock 5 as well as a Lock 5A, and there is no Lock 23. "Operation & Maintenance of Navigation Installations (OMNI) Reports". Rock Island District Engineers. Archived from the original on 2006-07-19. Retrieved 2006-04-27.
  17. ^ "U.S. Waterway System Facts, December 2005" (PDF). USACE Navigation Data Center. Archived from the original (PDF) on 2007-07-03. Retrieved 2006-04-27.
  18. ^ Walker, Brad (February 2010). "Big Price—Little Benefit: Proposed Locks on the Upper Mississippi and Illinois Rivers are not Economically Viable" (PDF). Nicollet Island Coalition. Retrieved 2017-07-13.

External links[edit]