Mobile Bay’s average depth is only about 10 feet, which is among the most-shallow for a bay of its size. It is approximately 32 miles “tall” (north to south), 23 miles across at its widest point, and about 10 miles across at the City of Mobile. A combination of wind and tide delivers salty Gulf waters from the south into the Bay that mix with varying amounts of freshwater from the Mobile-Tensaw River Delta. Due to the shallow nature of the bay, dynamic climatic conditions, and man-made hydrologic modifications, salinity conditions in the Bay are remarkably variable.
Several factors contribute to the dynamic salinity conditions that characterize Mobile Bay. Summer thunderstorms and winter cold fronts produce heavy downpours that contribute to an average of about 66 inches of rainfall annually – the highest average nationally for a city the size of Mobile – along with a relatively high frequency of tropical cyclone landfalls. Consequently river flows are naturally highly variable. The Bay is influenced by a single daily or “diurnal” tidal cycle with tide changes that average a little less than a foot and a half and maximum changes exceeding two and a half feet. The resulting hydrology is dynamic, complex, and necessary to support the diversity of plant and animals found in and around the Bay.
The Alabama State Port Authority (ASPA), established in 1928 as a State governmental agency, operates the deepwater port facilities in Mobile Bay. The port complex includes facilities for handling general cargo, such as containers, forest products, and metals, as well as liquid bulk and dry bulk cargo, such as chemicals, coal, iron ore, and steel. The port complex features more than four million square feet of warehouse space and open yards and almost 40 berths for ships. A 75-mile rail line links Port of Mobile facilities and provides connections to major freight railroads. In 2009 the port of Mobile ranked 14th(out of 68 ports) in the U. S. in total foreign trade and 12thin total domestic trade.
A little bit of History....Apparently, Spanish explorers sailed in the area of Mobile Bay as early as 1500, as the Bay was marked on early Spanish maps as Bahia del Espiritu Sancto (the Bay of the Holy Spirit). Just 27 years after Christopher Columbus first introduced America to the western world, Admiral Alvarez de Pineda, a Spanish explorer, became the first European to sail into the waters of Mobile Bay in 1519. It would be another twenty years before another European would actually take a step in today’s Alabama.
Between 1539 and 1541, the well-known explorer and marauder Hernando de Soto explored the area and encountered and destroyed a fortified Mobile Indian town of Mauvila, from which modern Mobile derives its name. This battle with Chief Tuskaloosa and his warriors took place somewhere north of present-day Mobile. While Tuskaloosa himself was neither killed nor captured, virtually all of the inhabitants of Mauvila were killed. The first white colonists in Alabama landed on the shores of Mobile Bay in 1559 under the leadership of Tristán de Luna y Arellano following a hurricane that destroyed most of their ships and much of their Pensacola Bay colony.
A Canadian born Frenchman, Pierre Le Moyne, Sieur d’Iberville would be the first European to leave a considerable mark on the history of Mobile. In the late 1600s the French government was laying plans to settle and therefore claim the mouth of the Mississippi River. The Spanish, upon learning of plans for a permanent French settlement on the Gulf, quickly scrambled to occupy Pensacola Bay in 1698, denying the French port facilities there. After Iberville’s first reconnaissance for a Mississippi settlement in 1699, he returned to the Gulf and began the establishment of warehouses and port facilities on Mobile Bay’s Dauphin Island because of the presence of a deep water harbor (Pelican Bay) and the strategic importance of slowing the Spanish and English march across the eastern frontier towards the Mississippi River. They named the island, “Massacre Island” because of the presence of some sixty skeletons that were found when they landed there. By 1701, Dauphin Island had become an important military post of the growing French colony of Louisiana, and Iberville’s brother, Jean Baptiste Le Moyne, Sieur d’Bienville, succeeded him as Governor of Louisiana (the first of three such tenures).
Upon Iberville’s recommendation, Bienville established the first “Mobile settlement” and the capital of French Louisiana in 1702 at a site upstream from Mobile Bay along the Tensaw River at 27-Mile Bluff. The settlement was built in proximity to Mobile Indian villages , and the fort that was its center was called Fort Louis de la Louisiane de Mobile (for their Grand Monarch and employer, King Louis the XIV). One purpose of locating that original settlement 26 miles upriver was to encourage settlement along the river. Topography was also a consideration, since there were no bluffs considered adequate at the river’s mouth. Within two years, in 1704, Fort Louis was the center of the French plans in the region. There were 80 houses in the town and a population of 259. This location allowed better access to the interior but unfortunately was susceptible to unpredictable and frequent flooding.
The town was relocated to the mouth of the Mobile River in 1711. There were several reasons for the move, including frequent flooding, outbreaks of disease, difficultiesproviding adequate defenses for the port at Dauphin Island, and to facilitate better communication and commerce with ocean vessels. A new fort, called Fort Conde after the King’s cousin, was established, and the town that grew around it evolved into present day Mobile. Two books were recommended by Research Historian Charles Torrey of the Museum of Mobile for detailed histories of colonial Mobile. Old Mobile, Fort Louis de la Louisiane 1702-1711 (1977) by Jay Higgenbotham, and Colonial Mobile (1898) by Peter Joseph Hamilton,a historical study of the Alabama-Tombigbee basin from the discovery of Mobile bay in 1519 until the demolition of Fort Charlotte in 1821, are among the best references to the colonial history of the Mobile Bay area. The French occupied Mobile until the Treaty of Paris in 1763 ceded the Louisiana territory (including Mobile) to England. The English re-named French Fort Conde, Fort Charlotte.
In 1780 during the Revolutionary War, Spain, an ally of the fledgling Continental government, attacked the British garrison at Fort Charlotte commanded by Captain Elias Durford. Under attack by troops led by General Bernardo de Galvez, Captain Durford destroyed the entire city of Mobile so that the houses and shops of the town could not provide cover for the attacking Spanish troops. On March 13, 1780, the British surrendered Fort Charlotte to de Galvez, ending England's claim to the modern state of Alabama. Mobile became part of the colony of Spanish West Florida and for over 30 years was controlled from Pensacola until 1813 when it was captured by American forces.
During the War of 1812, American General James Wilkinson took a force of troops from New Orleans to capture Mobile from the Spanish. Following Spanish surrender in April of 1813 the Mobile area was added to the existing Mississippi Territory of the United States. In March, 1817, Mississippi joined the union as a state, splitting the Mississippi Territory in half, and leaving Mobile, for the next two years, as part of the new Alabama Territory. After two years as a territory, the U.S. State of Alabama was formed, and Mobile became a voting region of the United States in 1819.
Mobile experienced a boom surrounding the export of cotton in the years leading up the Civil War, and following secession in 1861 it was heavily fortified by the Confederates. Union naval forces, under the command of Admiral David Farragut, blockaded the Bay, leading to the construction and operation of blockade runners who maintained a trickle of commerce into and out of the city. In August, 1864, after fighting past Forts Gaines and Morgan, which guarded the mouth of the Bay, Farragut defeated a small force of wooden Confederate gunboats and the ironclad CSS Tennessee in the Battle of Mobile Bay, where Farragut is purported to have said, “Damn the torpedoes, full speed ahead.” On May 25, 1865, weeks after dissolution of the Confederacy, an ammunition depot explosion killed 300 persons and destroyed a significant portion of the city of Mobile.
Other historical landmarks:
- 1868 Mobile’s first municipal sewer lines are laid.
- 1885 Middle Bay Light is built by the U. S. Lighthouse Service.
- 1886 Bienville Water Works is established and later purchased by the city.
- 1888 The Mobile Ship channel was deepened to 23 feet.
- 1902 First street pavement is laid within the City of Mobile.
- 1923 Alabama State Docks were authorized for construction and later opened.
- 1926 Battleship Parkway (the Causeway) built between Baldwin and Mobile Counties, provided an over-land route across the Bay for vehicular traffic and effectively dammed one of the major estuaries on the North American continent.
- 1941 The Bankhead Tunnel opens
- 1955 First Dauphin Island Bridge is completed, marking a transition in transportation to the Island from boat to automobile.
- 1964 Battleship U.S.S. Alabama is brought to Mobile.
- 1973 The George C. Wallace tunnel opens on Interstate 10.
- 1981 The I-10 Bayway is completed across Mobile Bay.
- 1982 The Gordon Persons/Dauphin Island Bridge is completed, replacing the original bridge destroyed by Hurricane Frederick in 1979.