Upper Mississippi River
The Upper Mississippi River near Harpers Ferry, Iowa
Location
CountryUS, Canada [1]
Physical characteristics
Source 
 • 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]
Mouth 
 • 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]
Discharge 
 • 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 the portion of the Mississippi River upstream of St. Louis, Missouri, United States,[1] at the confluence of its main tributary, the Missouri River.

History

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.

Characteristics

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.

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

Ecology

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 will provide additional benefits.[14]

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

Expansion proposals for locks

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

PoolLocalityLockMile marker(km)Distance(km)
USAF PoolMinneapolis MNUpper St. Anthony Falls Lock8541375  
LSAF PoolMinneapolis MNLower St. Anthony Falls Lock853137312
Pool 1Minneapolis MNLock 1848136558
Pool 2Hastings MNLock 281513123353
Pool 3Welch MNLock 379712831829
Pool 4Alma WILock 475312124471
Pool 5Minnesota City MNLock 573811881524
Pool 5AFountain City WILock 5A72811721016
Pool 6Trempealeau WILock 671411501423
Pool 7La Crescent MNLock 770311321118
Pool 8Genoa WILock 867910932439
Pool 9Eastman WILock 964810433150
Pool 10Guttenberg IALock 106159903353
Pool 11Dubuque IALock 115839393252
Pool 12Bellevue IALock 125578972642
Pool 13Clinton IALock 135228403556
Pool 14LeClaire IALock 144937942947
Pool 15Rock Island ILLock 154837781016
Pool 16Illinois City ILLock 164577362642
Pool 17New Boston ILLock 174377042032
Pool 18Gladstone ILLock 184106602743
Pool 19Keokuk IALock 193645864674
Pool 20Canton MOLock 203435522134
Pool 21Quincy ILLock 213255231829
Pool 22New London MOLock 223014852439
Pool 24Clarksville MOLock 242734402845
Pool 25Winfield MOLock 252413883252
Mel Price PoolEast Alton ILMelvin Price Lock2013244064
Pool 27Granite City ILLock 271852981626

See also

References

  1. 1 2 3 4 "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. 1 2 3 "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. Retrieved 2008-04-11.
  15. ↑ Marcia Zarley Taylor (8 March 2006). "River debate continues". AgWeb. Retrieved 2006-03-13.
  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.
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