Upper Mississippi River
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| Upper Mississippi River | |
|---|---|
| | |
| Origin | Lake Itasca, Minnesota |
| Mouth | Cairo, Illinois (flows into Lower Mississippi River) |
| Basin countries | US |
| Length | 2000 km (1250 mi) |
| Source elevation | 450 m (1475 ft)<ref>General Information about the Mississippi River. U.S. National Park Service. Retrieved on 2006-04-01.</ref> |
| Avg. discharge | 5796 m³/s (204,800 ft³/s)<ref>Background on Upper Mississippi River Basin. EPA: Mississippi River Basin & Gulf of Mexico Hypoxia. Retrieved on 2006-04-01.</ref> |
| Basin area | 8540 km² (3296 mi²)<ref>Wlosinski, Joseph, et al. Habitat Changes in the Upper Mississippi River Floodplain. National Biological Service: Our Living Resources. Retrieved on 2006-04-01.</ref> |
- See also: Mississippi River
The Upper Mississippi River is the portion of the Mississippi River upstream of Cairo, Illinois, United States. From the headwaters at Lake Itasca, Minnesota, the river flows approximately 2000 kilometers (1250 mi) to Cairo, where it is joined by the Ohio River to form the Lower Mississippi River.<ref>Old Man River: History along the Mississippi. Herbert Hoover Presidential Library. Retrieved on 2006-03-12. </ref><ref>Upper Mississippi River Region. Rock Island District Engineers. Retrieved on 2006-03-12.</ref>
Unlike the Lower Mississippi, 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.<ref>About the Upper Mississippi River System. USGS Upper Midwest Environmental Sciences Center. Retrieved on 2006-03-13.</ref> A primary reason for damming the river is to facilitate barge transportation. The dams regulate water levels for the Upper, and play a major part in regulating levels on the Lower Mississippi.
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[edit] Ecology
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, Black, and Kaskaskia Rivers.<ref name="umrbafacts">Basin Facts. Upper Mississippi River Basin Association. Retrieved on 2006-04-01.</ref>
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, bottom-land forest, islands, channels, backwater lakes and sloughs.<ref>About the refuges. Friends of the Upper Mississippi River Refuges. Retrieved on 2006-04-01. </ref><ref name="umrbafacts" />
Most of the Upper Mississippi River, though, is not clean enough to allow fish consumption or swimming. Fertilizers and animal and human waste have contributed to high levels of nitrogen and phosphorus throughout the river basin. These nutrients initiate a chemical reaction which reduces the amount of oxygen dissolved in the water, which in turn affects a number of riverine species. The phenomenon also contributes to a hypoxic "dead zone" in the Gulf of Mexico.<ref>Army Corps Reform: The Mississippi River. American Rivers. Retrieved on 2006-04-02.</ref>
[edit] Navigation
Navigation locks allow towboats, barges, and other vessels to transit the dams. Approximately 1350 kilometers (850 mi), from the head of navigation near Minneapolis-St. Paul down to Cairo, has been made suitable for commercial navigation with a depth of 2.75 meters (9 ft).<ref name="umrbafacts" /> The agriculture and barge transportation industries have lobbied in the late 20th and early 21st centuries for a multi-billion dollar project to replace the aging lock and dam system. Some environmental groups and advocates of budgetary restraint argue that the project lacks economic justification.<ref>Marcia Zarley Taylor (08 March 2006). River debate continues. AgWeb. Retrieved on 2006-03-13.</ref>
Each lock & 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. The locks provide a collective 123 meters (404 ft) of lift.<ref>U.S. Waterway System Facts, December 2005 (PDF). USACE Navigation Data Center. Retrieved on 2006-04-27.</ref> Note that there is a Lock 5 as well as a Lock 5A. Note also that there is no Lock 23.<ref>Operation & Maintenance of Navigation Installations (OMNI) Reports. Rock Island District Engineers. Retrieved on 2006-04-27.</ref>
[edit] List of pools and locks
[edit] References
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