The Lower Mississippi River is the portion of the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...

downstream of

Cairo Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the capital of Egypt and its largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metro ...

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

. From the

confluence In geography, a confluence (also: ''conflux'') occurs where two or more flowing bodies of water join to form a single channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main stem); o ...

of the

Ohio River The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illino ...

and

Upper Mississippi River The Upper Mississippi River is the portion of the Mississippi River upstream of St. Louis, Missouri, United States, at the confluence of its main tributary, the Missouri River. History In terms of geologic and hydrographic history, the Upper ...

at Cairo, the Lower flows just under 1000 miles (1600 km) to the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

. It is the most heavily travelled component of the Mississippi River System.

Structures

Unlike on the upper rivers, there are no locks or dams on the Lower Mississippi. The river is, however, constrained by levees and

dikes Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes, ...

to control flooding and secure a navigation channel for

barges Barge nowadays generally refers to a flat-bottomed boat, flat-bottomed inland waterway vessel which does not have its own means of mechanical propulsion. The first modern barges were pulled by tugs, but nowadays most are pushed by Pusher (boat) ...

. The Old River Control Structure, the

Bonnet Carré Spillway The Bonnet Carré Spillway is a flood control operation in the Lower Mississippi Valley. Located in St. Charles Parish, Louisiana, about west of New Orleans, it allows floodwaters from the Mississippi River to flow into Lake Pontchartrain and ...

, the Mississippi River – Gulf Outlet Canal and other man-made structures on the lower reaches of the river seek to manipulate the flow of water in the vicinity of

New Orleans New Orleans ( , ,New Orleans
Merriam-Webster. ; french: La Nouvelle-Orléans , es, Nuev ...

History

The political and engineering focus in the 20th century was to separate the Lower Mississippi River from its

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

. Levees and channelization—along with substantial loss of bottomland forests to agriculture in the

alluvial valley Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...

—have resulted in a loss of wildlife and fish habitat, decreased water quality, and an expansion of the hypoxic zone in the

. Agricultural

runoff Runoff, run-off or RUNOFF may refer to: * RUNOFF, the first computer text-formatting program * Runoff or run-off, another name for bleed, printing that lies beyond the edges to which a printed sheet is trimmed * Runoff or run-off, a stock market ...

has resulted in increased

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids can ...

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

ation, pollution from

pesticides Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampric ...

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

to aquatic organisms, oxygen depletion and

eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...

Navigation

Channel depth of 9 feet is maintained by the Corps of Engineers from

St. Louis, Missouri St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi River, Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the Greater St. Louis, ...

Baton Rouge, Louisiana Baton Rouge ( ; ) is a city in and the capital of the U.S. state of Louisiana. Located the eastern bank of the Mississippi River, it is the parish seat of East Baton Rouge Parish, Louisiana's most populous parish—the equivalent of counties i ...

On the lower Mississippi, from Baton Rouge to the Gulf, the navigation depth is 45 feet, allowing for container ships and cruise ships to dock at the

Port of New Orleans The Port of New Orleans is an embarkation port for cruise passengers. It is also Louisiana’s only international container port. The port generates $100 million in revenue annually through its four lines of business – cargo (46%), rail (31%) ...

and bulk cargo ships shorter than 150 foot air draft to fit under the Huey P. Long Bridge and traverse the Mississippi to Baton Rouge. There is a feasibility study to dredge this portion of the river to 50 feet to allow

New Panamax Panamax and New Panamax (or Neopanamax) are terms for the size limits for ships travelling through the Panama Canal. The limits and requirements are published by the Panama Canal Authority (ACP) in a publication titled "Vessel Requirements". ...

ship depths. Barge rates

References

{{coord, 33, 45, N, 89, 45, W, scale:2500000, display=title * Freshwater ecoregions Ecoregions of the United States

Structures

History

Navigation

See also

References