San Francisco Bay

The San Francisco Bay (in English: San Francisco Bay) is a shallow bay and estuary through which approximately forty percent of the water of the state of California (United States) is drained, which comes from the Sacramento and San Joaquin from the Sierra Nevada mountains, and empties into the Pacific Ocean.

Technically, both rivers flow into Suisun Bay, which flows through the Carquinez Strait to meet the Napa River at the entrance to San Pablo Bay, which joins at the end of its southern part with San Francisco Bay, but all the group of interconnected bays is often referred to as San Francisco Bay.

According to allpubliclibraries, the San Francisco Bay is located in the state of California, on the west coast of the United States, surrounded by a contiguous region known as the San Francisco Bay Area (in English, San Francisco Bay Area), dominated by the large cities of San Francisco, Oakland and San Jose.


The bay was discovered by the first human beings who inhabited it, from 11000 BC. n. and.

In the year 1769, the Spanish sailors who crossed the west coast of what is now the United States, led by the Spanish explorer Gaspar de Portolá, were unable to find the port of Monterrey (California), then they continued north until near what is currently the beach of Pacifica (California), about 30 km south of the current Golden Gate Bridge. Short of food and water, Portolá, with an expedition of 63 men and 200 horses, left the coast to travel inland, reaching the 370 m summit of Sweeney Ridge (31 km south of the present Golden Gate Bridge), from where November 4, 1769 saw San Francisco bay. Sweeney Ridge is located in northern San Mateo County and is now part of the Golden Gate National Recreation Area where a monument marks the site of discovery. The site is listed in the National Register of Historic Places (NPS-68000022) as “No. 394: Site of the Discovery of San Francisco Bay”. In fact, the place was not discovered by Europeans, because it had been inhabited by its true discoverers for about 13,000 years.

The first European to enter the bay is believed to have been the Spanish explorer Juan de Ayala, who passed through the Golden Gate strait on August 5, 1775 on his ship San Carlos, and moored in a bay on Angel Island now known as Ayala Cove. This famous bay was the center of American settlement in the Wild West during the 19th century. From the 1820s onward, American presidents and expansionists coveted the bay as a great natural harbor on the Pacific Ocean.. After many unsuccessful efforts to purchase the bay and various areas around it, the United States Navy and Army seized the region belonging to Mexico during the American Intervention in Mexico (1845 – 1848). The 2 of February of 1848 California was annexed to the United States with the signing of the Treaty of Guadalupe Hidalgo. A year and a half later, California applied to join the United States on December 3, 1849. and was accepted as the 31st state of the union on September 9, 1850. During the fever of gold in California in the years 1848 – 1850, the San Francisco Bay turned to the instant one of the largest ports in the world, dominating shipping and transportation in the American West until the last years of the nineteenth century. The bay’s regional importance peaked when the transcontinental railroad reached its western terminus at Alameda on September 6, 1869. The terminal was moved to the Oakland Pier two months later, on November 8, 1869.

The San Francisco Bay continues to support one of the densest industrial and urban production establishments in the United States. The San Francisco Bay Area is the second largest urban area in the American West with approximately 8 million residents.


The bay covers between 1040 and 4160 square kilometers, depending on which sub-bays (such as San Pablo’s), estuaries, swamps, etc. are included in the measure. The main part of the bay measures 5 to 20 km wide from East to West and between 77 and 97 km from North to South.

The bay was navigable in its southern part to San José until the 1850s, when hydraulic gold mining dumped massive amounts of sediment from the rivers that were deposited in those parts of the bay that had little or no current. Later, the wetlands and estuaries were artificially filled in, reducing the size of the bay since the mid- 1800s by about a third. Recently, large areas of wetlands have been restored, confusing the question of the size of the bay.

Despite its value as a canal and port, many thousands of acres of marshy wetlands that form the edges of the bay were for many years considered wasted space. As a result, the soil was excavated for canal construction or dredging projects that was often dumped into wetlands and other parts of the bay as a garbage dump. From the mid- 1800s to the late 1900s, more than a third of the original bay was filled in and often built into it.

The deep, moist terrain in these areas is conducive to liquefaction during earthquakes, and most of the major damage near the bay in the 1989 Loma Prieta earthquake occurred to structures in these areas. The San Francisco Marina District, heavily damaged by the 1989 earthquake, was built on landfills that had been placed there for the San Francisco World’s Fair, although liquefaction did not occur on a large scale.

In the 1990s, San Francisco International Airport made a proposal to fill in hundreds of acres to expand its crowded international runways in exchange for purchasing other parts of the bay and turning them back into wetlands. The idea was, and still is, controversial.

There are four large islands in the San Francisco Bay. Secluded in the center of the bay is Alcatraz, where the famous federal penitentiary is located. The mountainous island “Yerba Buena” is pierced by a tunnel that joins the East and West margins of the San Francisco-Oakland Bay Bridge. Attached to it by its northern part is the artificial island Treasure Island, site of the Universal Exhibition of 1939. Closer to shore, Angel Islandwas known as the [Ellis Island]] of the West because it served as an entry point for immigrants from East Asia. The Strait of Mapache, between the city ​​of Tiburon and Angel Island, is the deepest part of the bay. Alcatraz Island’s federal prison is no longer operational, and the complex is now a popular tourist spot.


The San Francisco Bay is thought to represent a cleft under the earth’s crust between the San Andreas fault to the west and the Hayward fault to the east, although the precise nature of this hypothesis remains under study. This hypothesis establishes that during the last ice age, the basin now filled by the bay was a large linear valley with small hills, similar to most of the coastal mountain valleys. The rivers of the central valley flowed into the sea through a canyon where the Golden Gate Strait is now. When the great ice caps melted, the sea level rose 300 feet in 4,000 years, and the valley filled with water from the Pacific Ocean, turning into a bay. The little hills became islands.


Despite its urban and industrial character, the San Francisco Bay and the Sacramentoand San Joaquin river delta contain what are perhaps the most important ecological habitats in California. California Dungeness crab (cancer magister), Pacific halibut, and Pacific salmon fishing grounds rely on the bay as a breeding ground. The few salt marshes that still exist today represent the majority of existing salt marshes in California, supporting several endangered species and providing key ecosystem services, such as the leaching of pollutants and sediment from rivers.

The bay is a key link on the Pacific Flyway, an important north-south travel route for America’s migratory birds, stretching from Alaska to Patagonia. Millions of waterfowl annually use the bay’s shoals for refuge. Two endangered species of birds are found here: the California Lesser Tern (Stérnula Antillarum Brownii) and the California Rail (Rallus Longuirrostris Obsoletus). The exposed bay silt provides important foraging grounds for different species of charadriiformes, but the underlying layers of the silt pose geological hazards to nearby structures in many parts of the perimeter of the had. It is part of the hemispheric network of shorebird reserves as a hemispheric category site.

San Francisco Bay provided the first national wildlife refuge, Oakland’s Merritt Man-Made Lake (built in the 1860s) and America’s first urban National Wildlife Refuge, the San Francisco Bay National Wildlife Refuge (SFBNWR) (1972). Most of the SFBNWRs consist of salt evaporation ponds purchased or leased from the Leslie Salt Company and its successors, Cargill. These ponds produce the salt for various industrial purposes, such as chlorine bleach and plastics manufacturing, as well as supporting dense populations of brine shrimp, for use as feeding grounds for waterfowl.

In 2003, California and Cargill entered into one of the largest private land purchases in American history, with the state and federal governments paying approximately $ 200 million for 65 km² of salt ponds in the South Bay. SFBNWR and state biologists hope to restore some recently purchased ponds as tidal wetlands.

The seasonal water temperature range in the bay is between about 8 ° C (46 ° F) and 23 ° C (73 ° F).

The popular humpback whale Humphrey entered San Francisco Bay twice on errant migrations, and was successfully rescued and diverted both times in the late 1980s and early 1990s. This happened again with Dawn and Delta, a mother and her calf, in 2007.

Industry, mining, and other uses of mercury have caused its widespread distribution in the bay, with its consequent consumption by phytoplankton and contamination of the bay’s fisheries. In November 2007, a ship named COSCO Busan collided with the San Francisco-Oakland Bay Bridge and 58,000 gallons of fuel oil were spilled, creating the largest oil spill in the region since 1996.


The San Francisco Bay has been crossed by ships since the arrival of Europeans. Indigenous peoples used their canoes to fish and collect clams along the coast. The age of sailing brought ships communicating with the rest of the world as well as serving as the first ferries and freighters within the bay and also between the bay and inland ports, such as Sacramento and Stockton. These were gradually replaced by steam powered ships beginning in the late 19th century. Soon several shipyards were established around the bay, which increased during wartime.

The San Francisco Bay is crossed by five bridges: the Golden Gate (which was the largest suspension bridge in the world by the length of its central span at the time of its construction), the Richmond-San Rafael, the San Francisco Bay- Oakland (known as the Bay Bridge), the Hayward-San Mateo and the Dumbarton Bridge. The bay is also crossed by the Transbay Tube, an underwater tunnel through which the Bay Area Rapid Transit (BART) circulates.

Before the construction of these infrastructures, trans-bay transportation was dominated by fleets of ferries operated by the Southern Pacific and the transit company Key System. However, in recent decades, ships have made a comeback, primarily serving Marin County commuters, alleviating the Golden Gate Bridge traffic bottleneck.

The bay also continues to serve as a major international shipping port, served by a large container facility operated by the Port of Oakland, and two smaller facilities in Richmond and San Francisco.


San Francisco Bay is a mecca for lovers of water sports, both boats and kitesurfing and sailing surfing, due to the uniform strong thermally generated winds from the west / northwest – Beaufort scale 6 (15-25 knots) is common during summer afternoons — and protection against the strong waves of the open sea. Yachting and regattas are very popular pastimes in the bay.

San Francisco Bay

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