The Mobile–Tensaw River Delta is the largest

river delta A river delta is a landform, archetypically triangular, created by the deposition of the sediments that are carried by the waters of a river, where the river merges with a body of slow-moving water or with a body of stagnant water. The creat ...

and

wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

. It encompasses about in a area and is the second-largest delta in the

contiguous United States The contiguous United States, also known as the U.S. mainland, officially referred to as the conterminous United States, consists of the 48 adjoining U.S. states and the District of Columbia of the United States in central North America. The te ...

. This large river delta is around 45 mi long and averages 8 mi wide, being 16 mi wide at its widest point. It covers roughly 300 sq mi. Of its 260,000 acres, 20,000 acres consist of open water, 10,000 acres are marsh, 70,000 acres are swamp; and more than 85,000 acres are bottomland forest. It drains an area of about 44,000 sq miles, which includes 64% of Alabama and small portions of Georgia and Mississippi. The delta's northernmost point is the confluence of the Tombigbee and

Rivers and follows a southerly direction that ultimately opens into the head of

Mobile Bay Mobile Bay ( ) is a shallow inlet of the Gulf of Mexico, lying within the state of Alabama in the United States. Its mouth is formed by the Fort Morgan Peninsula on the eastern side and Dauphin Island, a barrier island on the western side. T ...

through the Mobile, Tensaw,

Apalachee The Apalachee were an Indigenous people of the Southeastern Woodlands, specifically an Indigenous people of Florida, who lived in the Florida Panhandle until the early 18th century. They lived between the Aucilla River and Ochlockonee River,Bobby ...

Middle Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ...

, Blakeley, and

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many countries in the Americas **Spanish cuisine **Spanish history **Spanish culture ...

Rivers near the Battleship Parkway. It is contained within sections of Baldwin, Clarke, Mobile,

Monroe Monroe or Monroes may refer to: People and fictional characters * Monroe (surname) * Monroe (given name) * James Monroe, 5th President of the United States * Marilyn Monroe, actress and model Places United States * Monroe, Arkansas, an unincorp ...

, and

Washington Washington most commonly refers to: * George Washington (1732–1799), the first president of the United States * Washington (state), a state in the Pacific Northwest of the United States * Washington, D.C., the capital of the United States ** A ...

Counties.South Alabama Regional Planning Commission
/ref>

Environment and ecology

The Mobile–Tensaw delta is ecologically important and includes a wide variety of habitats, including mesic

flood plains A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge.Goudie, ...

cypress Cypress is a common name for various coniferous trees or shrubs from the ''Cupressus'' genus of the '' Cupressaceae'' family, typically found in temperate climates and subtropical regions of Asia, Europe, and North America. The word ''cypress'' ...

- gum

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

s, tidal

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...

marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

es, bottomland forests, and submersed grass beds. As one of the most biologically diverse regions in both Alabama and the United States, it is home to 126 fish, 46 mammal, 69 reptile, 30 amphibian, and at least 300 bird species, including more than 110 of which nest in the region. The delta's considerable biodiversity has led to it being described as an "American

Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...

" by naturalist

E. O. Wilson Edward Osborne Wilson (June 10, 1929 – December 26, 2021) was an American biologist, naturalist, ecologist, and entomologist known for developing the field of sociobiology. Born in Alabama, Wilson found an early interest in nature and frequ ...

. Margaret Renkl has written about the delta and its vulnerability to coal ash pollution from the James M. Barry Electric Generating Plant upstream along the Mobile River.

Natural history

The delta lies in a river valley that began forming several million years ago. Many separate inland streams joined as they flowed southward across land, which was once covered by the

Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...

. By the end of the last major

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...

(around 18,000 years ago), when the sea level was much lower and Alabama's coastline was about south of its present location, the waterways of the delta valley extended much farther than their current-day southern termination at the head of Mobile Bay. As the ice age ended and global temperatures increased, sea levels began to rise again to their present-day level."Mobile–Tensaw Delta"
Encyclopedia of Alabama

History

Humans inhabited the delta region at least as far back as 5,000 years ago. During the Mississippian period, people of the Pensacola culture built earthen

mound A mound is a wikt:heaped, heaped pile of soil, earth, gravel, sand, rock (geology), rocks, or debris. Most commonly, mounds are earthen formations such as hills and mountains, particularly if they appear artificial. A mound may be any rounded ...

s along Bottle Creek and the Tensaw River. During the late prehistoric period, other peoples moved into the area, including the Taensas (Tensaw), the Creek, and the

Choctaw The Choctaw ( ) people are one of the Indigenous peoples of the Southeastern Woodlands of the United States, originally based in what is now Louisiana, Mississippi and Alabama. The Choctaw language is a Western Muskogean language. Today, Choct ...

. In the 16th century, the area was visited by Spanish forces. French explorers arrived in the last years of the 17th century, eventually settling colonial Mobile in 1702 at Twenty-seven Mile Bluff on the Mobile River. During the

Creek War The Creek War (also the Red Stick War or the Creek Civil War) was a regional conflict between opposing Native American factions, European powers, and the United States during the early 19th century. The Creek War began as a conflict within th ...

, Red Stick Creeks attacked Fort Mims near the confluence of the Alabama and Tombigbee Rivers in August 1813, where they killed most of the mixed-blood Tensaw and Lower Town Creeks, intermarried whites, slaves, and nearly 275 militia. The

schooner A schooner ( ) is a type of sailing ship, sailing vessel defined by its Rig (sailing), rig: fore-and-aft rigged on all of two or more Mast (sailing), masts and, in the case of a two-masted schooner, the foremast generally being shorter than t ...

'' Clotilda'' arrived in the delta on July 7, 1860, carrying 103 enslaved West Africans captured in

Dahomey The Kingdom of Dahomey () was a West African List of kingdoms in Africa throughout history, kingdom located within present-day Benin that existed from approximately 1600 until 1904. It developed on the Abomey Plateau amongst the Fon people in ...

, and was

scuttled Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull, typically by its crew opening holes in its hull. Scuttling may be performed to dispose of an abandoned, old, or captured vessel; to prevent the vesse ...

to prevent being prosecuted under the

Act Prohibiting Importation of Slaves The Act Prohibiting Importation of Slaves of 1807 (, enacted March 2, 1807) is a United States federal law that prohibited the importation of slaves into the United States. It took effect on January 1, 1808, the earliest date permitted by the U ...

. It was the last

slave ship Slave ships were large cargo ships specially built or converted from the 17th to the 19th century for transporting Slavery, slaves. Such ships were also known as "Guineamen" because the trade involved human trafficking to and from the Guinea ( ...

to enter the United States from the

Atlantic slave trade The Atlantic slave trade or transatlantic slave trade involved the transportation by slave traders of Slavery in Africa, enslaved African people to the Americas. European slave ships regularly used the triangular trade route and its Middle Pass ...

. After the

Emancipation Proclamation The Emancipation Proclamation, officially Proclamation 95, was a presidential proclamation and executive order issued by United States President Abraham Lincoln on January 1, 1863, during the American Civil War. The Proclamation had the eff ...

and the Thirteenth Amendment, many of the descendants of the ''Clotilda'' established the neighborhood of Africatown in Mobile. The last important battle of the

American Civil War The American Civil War (April 12, 1861May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States between the Union (American Civil War), Union ("the North") and the Confederate States of A ...

took place at the fortified town of Blakeley, located on the edge of the delta. A railroad line to connect Mobile to Montgomery, now part of the

CSX CSX Transportation , known colloquially as simply CSX, is a Railroad classes, Class I freight railroad company operating in the Eastern United States and the Canadian provinces of Ontario and Quebec. Operating about 21,000 route miles () of trac ...

system, opened across the delta in 1872. In the mid-1920s, the

Causeway A causeway is a track, road or railway on the upper point of an embankment across "a low, or wet place, or piece of water". It can be constructed of earth, masonry, wood, or concrete. One of the earliest known wooden causeways is the Sweet T ...

was built across the lowest part of the delta, connecting the western and eastern shores of Mobile Bay. Later,

I-65 Interstate 65 (I-65) is a major north–south interstate highway in the central United States. As with most primary interstates ending in 5, it is a major crosscountry, north–south route, connecting between the Great Lakes and the Gulf ...

and I-10 were constructed to span different parts of the area. An area of 190,000 acres of the delta was designated as a

National Natural Landmark The National Natural Landmarks (NNL) Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best e ...

in 1974, and four sites within the delta are also listed on the National Register of Historic Places.

Conservation issues

The Mobile–Tensaw River Delta and the adjacent Mobile estuary make up one of the largest wetland ecosystems in the United States, which is why protecting its wide range of biodiversity is a top priority for conservators. According to the Forever Wild ranking system, the Mobile-Tensaw Delta is one of its top priorities for protection. The Alabama Department of Conservation and Natural Resources (ADCNR) Game and Fish Division has also listed the Mobile-Tensaw Delta as one of their highest priorities for inclusion into the state wildlife management area system. The delta is one of 327 watersheds (of the 2,100 in the United States) to be deemed as being of irreplaceable value to conserving populations of all freshwater fish and mussel species at risk. Conservators' wide range of obstacles include hydrological alterations from man-made developments, stream pollution, the effects of upstream dams on stream flow, and effects of exotic invasive plant and animal species. The construction of the causeway in the 1920s is considered one of the most significant man-made obstructions to the delta. The causeway restricts sediment and water exchange with Mobile Bay resulting in an immensely higher sedimentation rate. The loss of hydrological connectivity between the delta and Mobile Bay reduced the salinity of the surrounding rivers and bay. Several species of fish, crustaceans, shellfish, and plant communities have been altered as a result of reduced salinity. Human activates resulting in upstream pollution within the Mobile River Basin have profound impacts on the Mobile-Tensaw Delta. Such pollution can include sediments, trace elements, metals, and pesticides draining from the basin upstream. Trace elements detected in fish tissue collected from sites throughout the Mobile River Basin suggest that aluminum, boron, copper, iron, manganese, selenium, strontium, and zinc are the most prevalent trace elements in the water. Upstream dams are put into place most commonly for the purposes of power generation, navigation, and flood control. Dams distort the natural hydrological flow by either physically restricting movement of wildlife or by creating large areas of inhospitable habitat. In both cases, populations are isolated, which can have detrimental effects on reproduction and natural migration. The Claiborne Lock and Dam, the largest dam upstream of the Mobile water basin, is located in Monroe County, Alabama. Exotic invasive plant and animal species have permanently altered the Mobile–Tensaw River Delta's ecology. Both types pose a threat to the native populations of wildlife that call the Mobile Delta home. Some of the most common non-native invasive plant species to conquer the delta include Eurasian watermilfoil, hydrilla, water hyacinth, and common salvinia. The most common invasive invertebrates include the Amazonian apple snails, Asiatic clams, and subtropical water fleas. Invasive fishes include common carp and grass carp. The invasive species that poses the largest threat to the entire ecosystem is wild swine. They are detrimental to the entire Alabama ecosystem because they eat almost any type of plant or animal materials, including agricultural crops, food discarded by humans, carrion, small mammals, birds, turtles, snakes, and amphibians. Humans are considered the only significant threat to this invasive hog population, which is why they are one of the only hunted animals in the state that are not monitored by a season for hunting.

Recreation

Boating Boating is the leisurely activity of travelling by boat, or the recreational use of a boat whether powerboats, sailboats, or man-powered vessels (such as rowing and paddle boats), focused on the travel itself, as well as sports activities, suc ...

and

fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment (Freshwater ecosystem, freshwater or Marine ecosystem, marine), but may also be caught from Fish stocking, stocked Body of water, ...

are popular in the Mobile Delta. Boat ramps and water-access points are abundant throughout the area. The Bartram Canoe Trail provides a system of waterways by which boaters may explore the delta. The area is known for its excellent

bird watching Birdwatching, or birding, is the observing of birds, either as a recreational activity or as a form of citizen science. A birdwatcher may observe by using their naked eye, by using a visual enhancement device such as binoculars or a telescop ...

.Alabama Coastal Bird Watching
/ref>

Hunting Hunting is the Human activity, human practice of seeking, pursuing, capturing, and killing wildlife or feral animals. The most common reasons for humans to hunt are to obtain the animal's body for meat and useful animal products (fur/hide (sk ...

is also a common pastime. Most of the Delta is very shallow water. To access these areas, airboats, canoes, kayaks, or other small craft are typically used.

References

External links

U.S. Geological Survey Map Mobile-Tensaw Delta Wildlife Management Area
at the U.S. Geological Survey Map Website. Retrieved February 2, 2023.
U.S. Geological Survey Map W. L. Holland Wildlife Management Area
at the U.S. Geological Survey Map Website. Retrieved February 2, 2023. {{DEFAULTSORT:Mobile-Tensaw River Delta Protected areas of Baldwin County, Alabama Protected areas of Mobile County, Alabama National Natural Landmarks in Alabama River deltas of the United States Mobile Bay Landforms of Baldwin County, Alabama Landforms of Mobile County, Alabama Estuaries of Alabama Wetlands of Alabama Alabama placenames of Native American origin