All About the Mobile & Tensaw River Basins

The Mobile Delta encompasses over 260,000 acres of lakes, streams, swamps, and bayous. The Delta is nearly 50% wetland cover, which includes estuaries, swamps, marshes, and bogs. The Delta is also home to old-growth bottomland hardwood forests as well as cypress-tupelo swamps.

Mobile Tensaw Delta. Image credit: Sydney Zinner

The Delta functions as a protective buffer to trap pollutants before reaching the Gulf of Mexico. Additionally, it serves as habitat for many rare and endangered wildlife species.

Estuaries that form part of the lower Delta are suitable habitat for both marine and freshwater species due to the mixing of salt and freshwater. This brackish water environment provides a productive “nursery” for many species, which helps foster the great aquatic biodiversity of the area.


303(d) Listed Waterbodies (displayed in red) in the Mobile-Tensaw River Basins. Data from the Alabama Department of Environmental Management.

In the Mobile-Tensaw Basin, there are 37, 288.36 miles of waterbodies listed as impaired on the Alabama Department of Environmental Management (ADEM) 303(d) List of Impaired Waters. The majority of these waterbodies are classified for Fish and Wildlife use, but one is listed for public water supply.

24 waterbodies are listed for metals (mercury) impairment via atmospheric deposition and contaminated sediments. Two waterbodies are listed for nutrient impairment from urban runoff and storm sewers. Two waterbodies are listed for organic enrichment from collection system failure, urban runoff and storm sewers.

Six waterbodies are listed for pathogen impairment for E.coli or Enterococcus from pasture grazing, collection system failure, urban runoff, and storm sewers.

Six waterbodies are listed for siltation impairment from land development.


America’s Amazon

The Mobile-Tensaw Delta is one of the most biodiverse places in the US and the world, and has even been deemed “America’s Amazon.” In addition to its exceptional biodiversity, the basin also boasts more tree species than any other region in North America.

Alabama Public Televsion’s Document, “America’s Amazon”, explores the Mobile-Tensaw River Delta.

Port of Mobile

The Port of Mobile was one of the largest ports in the south in the 1850s and is currently the ninth largest port in the US. As Alabama’s solitary port city, Mobile has served as a gateway for products including cotton, coal, timber, iron, steel, lumber, wood pulp, and chemicals. The port was a hub for shipbuilding during World War I and II and continues to be an important venue for shipbuilding companies.

The Tennessee-Tombigbee Waterway is a 234 mile river system that connects the Tennessee to the Mobile River and allows timber and coal exports.

Weeks Bay Estuary

The Weeks Bay National Estuarine Research Reserve (NERR), which was established in 1986 and is federally classified as an Outstanding Natural Resource Water, is part of the National Ocean and Atmospheric Administration’s (NOAA) National Estuarine Research Reserve System. Weeks Bay NERR is currently managed by the Alabama Department of Conservation and Natural Resources (ADCNR).

The estuary spans over 9,000 acres and is covered by forests, salt and freshwater marshes, diverse aquatic plants and bogs.

Weeks Bay Pitcher Plant Bog along the Kurt G. Wintermeyer Trail. Image Credit: Alan Cressler

Bon Secour National Wildlife Refuge

The National Wildlife Refuge (NWR) System, within the U.S. Fish and Wildlife Service, manages a national network of protected lands and waterbodies for the conservation of terrestrial and aquatic biodiversity.

The Bon Secour (meaning “safe harbor” in French) National Wildlife Refuge spans 7,000 acres and is part of a Gulf Coast group of NWRs which also includes the Mississippi Sandhill Crane NWR and Grand Bay NWR. The refuge provides sanctuary for native wildlife, including alligators, sea turtles, and over 370 species of birds, and is one of Alabama’s remaining undisturbed coastal barrier habitat.


Its no surprise that shrimp and oysters are one of the top agricultural commodities in the Mobile Basin, whether grown on farms or harvested wild from the Gulf. Other crops include peanuts, cotton, corn, soybeans and catfish.

Oyster Gardening. Image credit: ACES Flicker


Weeks Bay supports a lot of biodiversity and is home to species such as the brown pelican, eastern indigo snake, and the Alabama red-bellied turtle.

Brown Pelicans are a staple to coastal Alabama and a conservation success story. Back in the 1970s, conservationists successfully stopped the use of harmful pesticides, including DDT, in Brown Pelican habitat, which helped revive the species which was considered endangered at that time.

The Brown Pelican is a shorebird can reach a wingspan up to 7 feet, can weigh up to 8 pounds, and can live up to 30+ years. Brown pelicans nest in colonies, mostly on coastal islands. To deter predators, pelicans will spread guano on the eggs while in the nest. Their range extends from North America to South America.

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