Mississippi River Series- Part 1

This is the first of a series of briefs that will focus on the Mississippi River- its physical and hydrological characteristics, its exploration and explorers, the early studies to determine control strategies, its flood control infrastructure and flood events, its management, its role in the economic development of the United States, and other relevant matters.

Before serving the needs of European explorers and settlers, Native Americans used the river for thousands of years for transportation and fishing. The first written accounts about the river documented the extensive number of native tribes located in villages along its banks. The name of the river is attributed to the Ojibwe. The Ojibwe, also known as the Chippewa, were primarily located around the Great Lakes region in the United States and Canada. Their word for the river was Misi-ziibi which means “long river” not ‘father of waters” as often reported. Various names and spelling of names have been used for the river over the years, including Messipi, Missisipi, Riviere Saint Louis, and, by Spanish explorer Hernando de Soto, Rio del Espiritu Santo (“River of the Holy Spirit’).

As discussed in a previous blog, de Soto was the first European explorer to view the river. The date was May 8, 1541. He and his expedition did not explore the river but built flatboats, crossed the river and continued their expedition westward. Their westward progress was plagued by the death of their guide, harsh winter conditions, and encounters with hostile Native Americans causing the expedition to return to the west bank of the river. Unfortunately, de Soto died shortly thereafter of “fever” on May 21, 1542, and was buried along the banks of the river near present day McArthur, Arkansas or Ferriday, Louisiana. Some accounts indicate that his body was actually placed in a hollowed-out tree that was launched into the river.

Subsequently, the river has been explored and studied extensively but it was not until 1897 that the Congress created the Mississippi River Commission (MRC) and mandated the U.S. Corps of Engineers as the organization primarily responsible for the management the river and directly reporting to the Secretary of War and as of 1947, the Secretary of Defense. Specifically, the Act empowered the MRC to make surveys and investigations to make plans to the river channel, protect the banks, improve navigation, prevent destructive floods, and promote commerce. The Corps had been previously tasked with surveying the river for navigation improvements as early as the 1820’s. The mandated membership of the MRC consisted of three officers from the U.S. Corps of Engineers, one member from the U.S. Coast and Geodetic Survey (now National Oceanic and Atmospheric Agency- NOAA), and three civilians nominated by the President and confirmed by the Senate. The initial Corps of Engineers appointees were Brevet Major General Quincy A. Gilmore (appointed president of the Commission), Bvt. Brig. General Charles R. Suter, and Bvt. Brig. General Cyrus B. Comstock. The corresponding civilian appointees were James B. Eads, Benjamin Morgan Harrod, and Benjamin Harrison. Ten years later, Harrison, an attorney rather than an engineer, was to become the 23rd President of the United States. Harrod was a civil engineer and served as chief engineer for the State of Louisiana from 1877 to 1880, served on the Louisiana River Commission from 1879 to 1904, and was the New Orleans City Engineer from 1888 to 1902. The U.S. Coast and Geodetic Survey was Henry B. Mitchell. Eads and Brigadier General Andrew A. Humphreys, the Chief of Engineers, were to later conduct major studies of the Mississippi River and have major disagreements on the more effective ways to control river flooding.

From top to bottom: Eads, Humphreys, and Harrod.

For management purposes, the Mississippi River is divided into three sections: the Upper Mississippi from its headwaters at Lake Itasca in northern Minnesota to the confluence with the Missouri River; the Middle Mississippi from the Missouri River confluence to the confluence of the Ohio River; and the Lower Mississippi from the Ohio River confluence to the Head of Passes. Of course, the river continues downstream from the from the Head of Passes through a number of major and minor passes to the Gulf of Mexico. The following graphic combines the middle and upper sections of the river.

While various reference sources will cite slightly different mileages for the indicated sections of the river, the following listed mileages are judged to be accurate within less than one percent.

Upper Section

Headwaters at Lake Itasca, northern Minnesota to St. Anthony Falls, Minneapolis- 493 mi

St. Anthony Falls to Missouri River Confluence at St. Louis- 684 mi

Total- 1177 mi

Middle Section

Missouri River Confluence to Ohio River Confluence at Cairo, IL- 190 mi

Note: In some references, the middle section is considered to be a part of the upper section.

Lower Section

Ohio River Confluence to Head of Passes- 953 mi

Head of Passes to Gulf of Mexico via Southwest Pass- 20 mi

Total- 973 mi

The Head of Passes is designated mile zero (0 Above Head of Passes or AHP) for the lower section. Thus, Mile 953 AHP marks the location of the confluence of the Ohio River and the north end of the lower section and beginning of the middle section or the upper section if combined with the middle section.

As noted, this is a map of the Mississippi River Delta, a complex system of passes and low-lying land masses. The Head of Passes referred to earlier is located approximately at the convergence of the multiple passes from the Gulf to the major body of the river. The pass on the left side of the map is Southwest Pass; in the center is South Pass: to the right, a comparatively small but distinct pass is Pass a Loutre; and Main Pass, only partially depicted at the top of the map. It is noted that Pass a Loutre flows into Main Pass. Over the years, other passes have opened and then closed due to flooding, sedimentation, hurricane effects, and hydrologic processes.

Whereas the Southwest Pass is currently the major river navigation pass, the river outlet at South Pass is approximately 8 miles shorter to the Gulf than Southwest Pass. New Orleans is located about 95 river miles above the Head of Passes and, thus, 107 and 115 river miles from the Gulf via South Pass and Southwest Pass, respectively.

Given these distances for the three sections of the Mississippi River, the total length of the river is 2,340 miles from its source at Lake Itasca in Minnesota to its outlet into the Gulf of Mexico via Southwest Pass. That mileage coincides with the total published in a number but not all sources. For example, the U. S. National Park Service lists 2,350 miles as the total.

The river drains 41 percent of the area of the continental United States and is the fourth longest river and the third largest watershed in the world. It drains runoff from thirty-two states in the U.S. and two Canadian Provinces. Major tributaries to the river include the following rivers: Missouri, Arkansas, Illinois, and Ohio. Other rivers flow into the major tributaries and thus may be labeled “indirect tributaries”. These include the Monongahela and Allegheny Rivers that flow together at Pittsburgh to form the Ohio River; the Tennessee River that flows into the Ohio River; and the Wabash River that also flows into the Ohio River.

A distributary of the Mississippi River is the Atchafalaya River whose quantity of flow from the Mississippi River is regulated by the Old River Control Structure (ORCS) completed in 1963. Construction of the ORCS was motivated by a 1953 study that concluded that the Mississippi River could actually change its course to the Atchafalaya River by 1990 unless action was taken to control flow from the Mississippi River to the Atchafalaya River. After over 10 years of planning and construction, the ORCS was completed in 1964 as a means to control flow from the Mississippi to the Atchafalaya. The control system was expanded in 1986 by the addition of the Old River Control Auxiliary Structure (ORCAS) that is only used during floods to prevent damage to the ORCS due to high flow rates. Presently, approximately 30 percent of the flow of the Mississippi River is routed through the Old River Control Structure to the Atchafalaya River. The Old River Control Structure almost failed during the flood of 1973. Had that failure occurred, it would have resulted in a significant loss of flow in the current course of the Mississippi River and dramatic economic losses to the ports of New Orleans and Baton Rouge. Construction of the ORCAS was an action taken in response to the near failure of the ORCS.

The ORCS and ORCAS structures are located between the lower section mile markers 313 AHP and 314.5 AHP. In addition to the ORCS and the ORACS, the Old River Control Complex includes two bounding structures. To the north is the Sidney A. Murray, Jr. Hydroelectric Station and to the south is the Old River Lock that gives vessels access from the Mississippi River to the Atchafalaya River. The latter structure is at lower river mile 304 AHP, some 10 miles south of the ORCS. The Atchafalaya River route through the Old River Lock to the intersection with the GIWW saves in excess of 170 miles compared to continuing down the Mississippi River. If you look carefully at the photo to the left, beginning at its top and continuing downward, you will be able to identify the hydroelectric plant, the ORCS, and the ORACS. About ten miles downstream is the Old River Lock shown in the right photo.

Until the mid-20th century, the Red River contributed flow to the Atchafalaya River and, via Old River, the Mississippi River. Upon completion of the Old River Control structure, all of the flow of the Red River is directed to the Atchafalaya River.

Currently, the “head of navigation” of the Mississippi River is located at Upper St. Anthony Falls Lock and Dam, near Minneapolis. When constructed in 1963, navigation was able to move upstream to Coons Rapid Dam but the Upper St. Anthony Lock was closed in 2015 to prevent the spread of invasive Asian carp. The U. S. Corps of Engineers maintains a minimum 9-ft deep shipping channel between Port of Baton Rouge and Minneapolis and a minimum 45-ft deep shipping channel from Southwest Pass to the Port of Baton Rouge. However, a project was launched in September 2020 to deepen the shipping channel from the Gulf through Southwest Pass to Port of Baton Rouge from 45 ft. to 50 ft. As of August 2022, the channel had been deepened through Southwest Pass to lower river mile 175 AHP (Donaldsonville) but some 54 river miles short of the Port of Baton Rouge located at lower river mile 229 AHP. (Note: AHP refers to Above Head of Passes.) There are plans to further deepen the shipping channel to 55 ft. from the Gulf through Southwest Pass to the Port of Baton Rouge.

The system includes 28 locks and dams on the Upper Mississippi and seven locks along the Illinois River waterway.

As described in an earlier brief (The Industrial Canal: Design, Construction, and Connections), the eastern Gulf Intracoastal Waterway (GIWW) is connected to the Mississippi River via the Inner Harbor Navigation Canal Lock at New Orleans (Lower River Mile 92.6 AHP). On the west bank of the river, both the Harvey Lock (located at Lower River Mile 98.3 AHP) and the Algiers Lock (Lower River Mile 88 AHP) link with the Western GIWW that extends over 600 miles from the Harvey Lock to Brownsville, Texas. Mileage on the GIWW is designated as being either east of the Harvey Lock (EHL) or west of the Harvey Lock (WHL).

A link to the western GIWW via the Atchafalaya River is provided just south of the Port of Baton Rouge by the Port Allen Lock at Lower River Mile 228.3 AHP. This allows vessels traveling south on the river to save a considerable number of miles to the western GIWW or the Gulf of Mexico. Opened in 1961, the Port Allen Lock replaced the Plaquemine Lock that had been in operation from 1909 to 1949. The Plaquemine Lock at Lower River Mile 209 AHP connected the Mississippi River to the Atchafalaya River and thence to the Gulf via Bayou Plaquemine and has been designated as a National Historic Landmark. Access to the Gulf via this system for vessels travelling downriver significantly shortens the distance to the Gulf compared to continuing down the river. However, access via this route to the western section of the GIWW only became possible starting in 1934 with the completion of the GIWW section from the Mississippi River to Galveston; from the river to Corpus Christi in 1942; and the river to Brownsville in 1949. As noted earlier, Brownsville was and is the terminus of the western GIWW.

Having provided a somewhat comprehensive summary of the features of the river, with emphasis on the lower section, Part 2 will focus on the explorers, explorations, and studies of the river.

Sources

https://en.wikipedia.org/wiki/Old_River_Control_Structure

https://www.mvd.usace.army.mil/About/Mississippi-River-Commission-MRC/

https://www.usace.army.mil/About/History/Historical-Vignettes/Civil-Engineering/088-

Mississippi-River-Commission/

https://www.britannica.com/place/Mississippi-River

https://en.wikipedia.org/wiki/Mississippi_River

https://www.txdot.gov/projects/planning/gulf-intracoastal-waterway.html

https://en.wikipedia.org/wiki/Gulf_Intracoastal_Waterway

https://en.wikipedia.org/wiki/Hernando_de_Soto

https://www.mvn.usace.army.mil/Portals/56/docs/PAO/Brochures/FinalPALBrochure.pdf

https://en.wikipedia.org/wiki/Mississippi_River_System

https://www.nps.gov/miss/riverfacts.htm