San Francisco Bay is a shallow, productive
estuaryAn estuary is a semi-enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries are thus subject to both marine influences, such as tides, waves, and the influx of saline water; and riverine influences, such as flows of...
through which water draining from approximately forty percent of
CaliforniaCalifornia is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil...
, flowing in the
SacramentoThe Sacramento River is the longest river entirely within the state of California. Starting at the confluence of the South Fork and Middle Fork of the Sacramento River, near Mount Shasta in the Cascade Range mountains, the Sacramento flows south for , through the northern Central Valley of...
and
San JoaquinThe San Joaquin River , long, is the second-longest river in California. The average unimpaired runoff of the main stem of the river at Millerton Reservoir is about 1.8 million acre feet per year . The San Joaquin and its eight major tributaries drain about of California's San Joaquin Valley...
riverA river is a natural watercourse, usually freshwater, flowing toward an ocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water...
s from the Sierra Nevada
mountainA mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill. The adjective montane is used to describe mountainous areas and things associated with them...
s, enters the
Pacific OceanThe Pacific Ocean is the largest of the Earth's oceanic divisions. Its name is derived from the Latin name Tepre Pacificum, "peaceful sea", bestowed upon it by the Portuguese explorer Ferdinand Magellan. It extends from the Arctic in the north to Antarctica in the south, bounded by Asia and...
. Technically, both rivers flow into
Suisun BaySuisun Bay is a shallow tidal estuary located at in northern California, USA. It lies at the confluence of the Sacramento and San Joaquin Rivers, thus forming the entrance to the Sacramento-San Joaquin River Delta, an inverted river delta. Suisun Marsh is the tidal marsh land located to the...
, which flows through the
Carquinez StraitThe Carquinez Strait is a narrow tidal strait in northern California. It is part of the tidal estuary of the Sacramento and the San Joaquin rivers as they drain into the San Francisco Bay...
to meet with the
Napa RiverThe Napa River, approximately 55 miles long, is a river in the U.S. state of California. It drains a famous wine-growing region, called the Napa Valley, in the mountains northeast of San Francisco. Milliken Creek is a tributary of the Napa River....
at the entrance to
San Pablo BaySan Pablo Bay is a shallow tidal estuary that forms the northern extension of San Francisco Bay in northern California in the United States. It receives the waters of the Sacramento and San Joaquin rivers, via Suisun Bay and the Carquinez Strait on its east end, and it connects to the Pacific Ocean...
, which connects at its south end to San Francisco Bay, although the entire group of interconnected bays are often referred to as "San Francisco Bay."
San Francisco Bay is located in the
U.S.The United States of America is a federal constitutional republic comprising fifty states and a federal district...
state of California, surrounded by a contiguous region known as the
San Francisco Bay AreaThe San Francisco Bay Area, commonly known as the Bay Area, or the Yay Area, is a metropolitan region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses large cities such as San Francisco, Oakland, and San Jose, along with smaller urban and...
, dominated by the large cities San Francisco,
OaklandOakland is the eighth-largest city in the U.S. state of California and a major West Coast port city, located on San Francisco Bay about eight miles east of the City of San Francisco. Oakland is a major hub city for the Bay Area subregion collectively called the East Bay, and it is the county seat...
and
San JoseSan Jose or San José is the third-largest city in California and the tenth-largest in the United States. The county seat of Santa Clara County, it is located at the southern end of the San Francisco Bay Area, a region commonly referred to as Silicon Valley...
.
Size
The Bay covers somewhere between 400 and 1,600 square miles (1,040 to 4,160 square kilometers), depending on which sub-bays (such as San Pablo Bay), estuaries,
wetlandA wetland is an area of land whose soil is saturated with moisture either permanently or seasonally. Such areas may also be covered partially or completely by shallow pools of water. Wetlands include swamps, marshes, and bogs, among others. The water found in wetlands can be saltwater, freshwater,...
s, and so on are included in the measurement. The main part of the Bay measures 3 to 12 miles (5 to 20 km) wide east-to-west and somewhere between
1 and
2 north-to-south.
The bay was navigable as far south as San Jose until the 1850s, when
hydraulic miningHydraulic mining, or hydraulicking, is a form of mining that employs water to dislodge rock material or move sediment. Previously, the use of a large volume of water had been developed by the Romans to remove overburden and then gold-bearing debris as in Las Médulas of Spain, and Dolaucothi in...
released massive amounts of sediment from the rivers that settled in those parts of the bay that had little or no current. Later, wetlands and inlets were deliberately filled in, reducing the Bay's size since the mid-1800s by as much as one third. Recently, large areas of wetlands have been restored, further confusing the issue of the Bay's size. Despite its value as a waterway and
harborA harbor or harbour , or haven, is a place where ships may shelter from the weather or are stored. Harbors can be man-made or natural. A man-made harbor will have sea walls or breakwaters and may require dredging. A natural harbor is surrounded on most sides by land.Harbors and ports are often...
, many thousands of
acreThe acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre....
s of marshy wetlands forming the edges of the bay were considered for many years to be wasted space. As a result, soil excavated for building projects or dredged from channels was often dumped onto the wetlands and other parts of the bay as landfill. From the mid-1800s through the late 1900s, more than a third of the original bay was filled and often built on. The deep, damp soil in these areas is subject to liquefaction during
earthquakeAn earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph...
s, and most of the major damage close to the Bay in the
Loma Prieta earthquakeThe Loma Prieta earthquake, also known as the Quake of '89 and the World Series Earthquake, was a major earthquake that struck the San Francisco Bay Area of California on October 17, 1989, at 5:04 p.m. local time...
of 1989 occurred to structures on these areas. The Marina District of San Francisco, hard hit by the 1989 earthquake, was built on fill that had been placed there for the
Panama-Pacific International Exposition (1915)The Panama-Pacific International Exposition was a world's fair held in San Francisco, California between February 20 and December 4 in 1915. Its ostensible purpose was to celebrate the completion of the Panama Canal, but it was widely seen in the city as an opportunity to showcase its recovery...
, although liquefaction did not occur on a large scale. In the 1990s,
San Francisco International AirportSan Francisco International Airport is a major international airport located south of downtown San Francisco, California, United States, adjacent to the cities of Millbrae and San Bruno in unincorporated San Mateo County. It is often referred to as SFO...
proposed filling in hundreds more acres to extend its overcrowded international
runwayA runway is a strip of land at an airport on which aircraft can take off and land and forms part of the maneuvering area. Runways may be a man-made surface or a natural surface .By extension, the term has come to mean, in addition, any long, flat, straight area, such as that used in fashion...
s in exchange for purchasing other parts of the bay and converting them back to wetlands. The idea was, and remains, controversial. (For further details, see the "Bay Fill and Depth Profile" section.)
There are four large islands in San Francisco Bay. Isolated in the center of the Bay is Alcatraz, the site of the famous federal penitentiary. Mountainous
Yerba Buena IslandYerba Buena Island sits in the San Francisco Bay between San Francisco and Oakland, California. The Yerba Buena Tunnel runs through its center and connects the western and eastern spans of the San Francisco-Oakland Bay Bridge. It has had several other names over the decades: Sea Bird Island, Wood...
is pierced by a tunnel linking the east and west spans of the San Francisco – Oakland Bay Bridge. Attached to the north is the artificial and flat
Treasure IslandTreasure Island is an artificial island in the San Francisco Bay between San Francisco and Oakland. It is connected by a small isthmus to Yerba Buena Island. It was created in 1936 & 1937, from fill dredged from the bay, for the Golden Gate International Exposition...
, site of the 1939
Golden Gate International ExpositionThe Golden Gate International Exposition , held at San Francisco, California's Treasure Island, was a World's Fair that celebrated, among other things, the city's two newly-built bridges. The San Francisco – Oakland Bay Bridge was dedicated in 1936 and the Golden Gate Bridge was dedicated in 1937...
. Closest to shore,
Angel IslandAngel Island is an island in San Francisco Bay that offers expansive views of the San Francisco skyline, the Marin County Headlands and Mount Tamalpais. The entire island is included within Angel Island State Park, and is administered by California State Parks. It has been used for a variety of...
was known as "
Ellis IslandEllis Island, at the mouth of the Hudson River in New York Harbor, is the location of what was from January 1, 1892, until November 12, 1954 the main entry facility for immigrants entering the United States; the facility replaced the state-run Castle Garden Immigration Depot in Manhattan...
West" because it served as the entry point for immigrants from
East AsiaEast Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms. Geographically and geo-politically, it covers about , or about 28 percent of the Asian continent, about 15 percent bigger than the area of Europe, though some categorize Tibet, Xinjiang,...
. Raccoon Strait, between
TiburonTiburon is an incorporated town in Marin County, California. It occupies most of the Tiburon Peninsula, which reaches south into the San Francisco Bay. The smaller city of Belvedere occupies the south-east part of the peninsula and is contiguous with Tiburon...
and Angel Island, is the deepest part of the Bay. The federal prison on
Alcatraz IslandAlcatraz Island is an island located in the San Francisco Bay, offshore from San Francisco, California. Often referred to as The Rock, the small island early-on served as a lighthouse, a military fortification, a military prison, and a federal prison until 1963...
no longer functions, and the complex is now a popular tourist site.
Geology
San Francisco Bay is thought to represent a down-warping of the earth's crust between the
San Andreas FaultThe San Andreas Fault is a continental transform fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...
to the west and the Hayward Fault to the east, although the precise nature of this continues to be studied. During the last
ice ageThe general term "ice age" or, more precisely, "glacial age" denotes a geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in an expansion of continental ice sheets, polar ice sheets and alpine glaciers. Within a long-term ice age, individual...
, the basin now filled by the bay was a large linear valley with small hills, similar to most of the valleys of the Coast Ranges. The rivers of the Central Valley ran out to sea through a canyon which is now the Golden Gate. As the great ice sheets melted, sea level rose 300 feet over 4,000 years, and the valley filled with water from the Pacific, becoming a bay. The small hills became islands.
History
The first recorded
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
an discovery of San Francisco Bay was on November 4, 1769 when
SpanishSpain , officially the Kingdom of Spain , is a country located in southwestern Europe on the Iberian Peninsula.
[The Spanish constitution does not establish any official denomination of the country, even though España , Estado español and Nación española are used interchangeably...]
explorer
Gaspar de PortolàGaspar de Portolà i Rovira was a soldier, governor of Baja and Alta California , explorer and founder of San Diego and Monterey. He was born in Os de Balaguer, province of Lleida, in Catalonia, Spain, of Spanish nobility. Don Portolà served as a soldier in the Spanish army in Italy and Portugal...
, unable to find the port of
Monterey, CaliforniaThe City of Monterey in Monterey County is located on Monterey Bay along the Pacific coast in Central California. Variants of the city's name are recorded as Monte Rey and Montery. Monterey lies at an elevation of 26 feet above sea level. As of 2005, the city population was 30,641...
, continued north close to what is now
PacificaPacifica is a city in San Mateo County, California, on the coast of the Pacific Ocean between San Francisco and Half Moon Bay.-Overview:The City of Pacifica is spread along a six mile stretch of the north central California coastal beach and hills, nestled in several small valleys spanning between...
and reached the summit of the high
Sweeney RidgeSweeney Ridge, a national park in Pacifica, California is part of the Golden Gate National Recreation Area. Historically, the ridge was the location of San Francisco Bay Discovery Site, as part of the Portolá Expedition on November 4, 1769.-Description:...
, where he sighted San Francisco Bay. Portola and his party did not realize what they had discovered, thinking they had arrived at a large arm of what is now called
Drakes BayDrakes Bay is a small bay on the coast of northern California in the United States, approximately 30 miles northwest of San Francisco at approximately 38 degrees north latitude. The bay is approximately 8 miles wide...
. At the time, Drakes Bay went by the name
Bahia de San Francisco and thus both bodies of water became associated with the name. Eventually, the larger, more important body of water fully appropriated the name
San Francisco Bay.
The first European to enter the bay is believed to have been the Spanish explorer
Juan de AyalaJuan Manuel de Ayala was a Spanish naval officer who played a significant role in the European exploration of California, since he and the crew of his ship the San Carlos are the first Europeans known to have entered the San Francisco Bay.Ayala was born in Osuna, Andalucía...
, who passed through the
Golden GateThe Golden Gate is the North American strait connecting San Francisco Bay to the Pacific Ocean. Since 1937 it has been spanned by the Golden Gate Bridge...
on August 5, 1775 in his ship the
San Carlos, and moored in a bay of
Angel IslandAngel Island is an island in San Francisco Bay that offers expansive views of the San Francisco skyline, the Marin County Headlands and Mount Tamalpais. The entire island is included within Angel Island State Park, and is administered by California State Parks. It has been used for a variety of...
now known as Ayala Cove.
This famous bay was the center of American settlement in the Far West during the 19th century. From the 1820s onward, American presidents and expansionists coveted the bay as a great natural harbor in the Pacific. After many failed efforts to buy the bay and varying areas around it, the
US NavyThe United States Navy is the sea branch of the U.S. Armed Forces. It is one of the seven uniformed services of the United States. As of 31 December 2008, the U.S. Navy had about 331,682 personnel on active duty and 124,000 in the Navy Reserve. It operates 283 ships in active service and more than...
and
ArmyThe United States Army is the branch of the United States Military responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military and is one of seven uniformed services...
seized the region from
MexicoThe United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
during the Mexican-American War (1845-1848). On February 2, 1848 California was annexed to the U.S. with the signing of the
Treaty of Guadalupe HidalgoThe Treaty of Guadalupe Hidalgo is the peace treaty, largely dictated by the United States to the interim government of a militarily occupied Mexico, that ended the Mexican-American War...
. A year and a half later, California requested 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 California
gold rushA gold rush is a period of feverish migration of workers into the area of a dramatic discovery of commercial quantities of gold.Gold rushes took place in the 19th century in Australia, Brazil, Canada, South Africa, and the United States....
of 1848-1850s, San Francisco Bay instantly became one of the world's greatest seaports, dominating shipping and transportation in the American West until the last years of the nineteenth century. The bay's regional importance became paramount when the
transcontinental railroadA Transcontinental Railroad is a railroad that crosses a continent from "coast-to-coast". Terminals are at or connected to different oceans. Because Europe is criss-crossed by railways, railroads within Europe are usually not considered transcontinental, the Orient Express perhaps being an...
reached its western terminus in
AlamedaAlameda is a city in Alameda County, California, United States. It is located on a small island of the same name next to Oakland in the San Francisco Bay. An additional part of the city is Bay Farm Island, which is adjacent to the Oakland International Airport. The city has a small town feeling...
on September 6, 1869. The terminus was switched to the
Oakland Long WharfThe Oakland Long Wharf, later known as the Oakland Pier or the SP Mole was a massive railroad wharf and ferry pier in Oakland, California. It was located at the foot of Seventh Street....
two months later on November 8, 1869.
San Francisco Bay continues to support some of the densest industrial production and urban settlement in the United States. The San Francisco Bay Area is the American West's second-largest urban area with approximately 8 million residents.
Ecology
Despite its urban and industrial character, San Francisco Bay and the
Sacramento-San Joaquin DeltaThe Sacramento-San Joaquin River Delta is an expansive inland river delta and estuary in northern California in the United States. It is formed at the western edge of the Central Valley by the confluence of the Sacramento- and San Joaquin-rivers and lies just east of where the rivers enter Suisun Bay...
remain perhaps California's most important
ecologicalEcology is the interdisciplinary scientific study of the interactions between organisms and the interactions of these organisms with their environment....
habitatsA habitat is an ecological or environmental area that is inhabited by a particular animal and plant species...
. California's
Dungeness crabThe Dungeness Crab is a species of crab that inhabits West Coast eelgrass beds and water bottoms all the way from Alaska's Aleutian Islands down to Santa Cruz, California. They are named after Dungeness, Washington, which is located approximately five miles north of Sequim and 15 miles east of...
, Pacific
halibutA halibut is a type of flatfish from the family of the right-eye flounders . This name is derived from haly and butt , alleged to be called so from being commonly eaten on holy-days...
, and Pacific
salmonSalmon is the common name for several species of fish of the family Salmonidae. Several other fish in the family are called trout; the difference is often attributed to the migratory life of the salmon as compared to the residential behaviour of trout, a distinction that holds true for the Salmo...
fisheries rely on the bay as a nursery. The few remaining salt marshes now represent most of California's remaining salt marsh, supporting a number of endangered
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
and providing key ecosystem services such as filtering pollutants and
sedimentSediment is any particulate matter that can be transported by fluid flow, and which eventually is deposited.Sediments are most often transported by water transported by wind and glaciers...
s from the rivers. Most famously, the bay is a key link in the
Pacific FlywayThe Pacific Flyway is a major north-south route of travel for migratory birds in the Americas, extending from Alaska to Patagonia. Every year, migratory birds travel some or all of this distance both in spring and in fall, following food sources, heading to breeding grounds, or travelling to...
. Millions of
waterfowlWaterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans.They are strong swimmers with medium to large bodies. They have historically been an important food source, and continue to be hunted as game, or raised as...
annually use the bay shallows as a refuge. Two
endangered speciesAn endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters. Also it could mean that due to deforestation there may be a lack of food and/or water...
of birds are found here: the
California least ternThe Least Tern is a species of tern that breeds in North America and locally in northern South America. It is closely related to, and was formerly often considered conspecific with, the Little Tern of the Old World...
and the
California clapper railThe California Clapper Rail is an endangered subspecies of the Clapper Rail . It is found principally in California's San Francisco Bay, and also in Monterey Bay and Morro Bay...
. Exposed
bay mudBay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacial cycles...
s provide important feeding areas for shorebirds, but underlying layers of bay mud pose geological hazards for structures near many parts of the bay perimeter. San Francisco Bay provided the nation's first wildlife refuge, Oakland's artificial
Lake MerrittLake Merritt is a large tidal lagoon that lies just east of downtown Oakland, California. It is surrounded by parkland and city neighborhoods. A popular 3.5 mile walking and jogging path runs along its perimeter...
(constructed in the 1860s) and America's first urban National Wildlife Refuge, the
Don Edwards San Francisco Bay National Wildlife RefugeDon Edwards San Francisco Bay National Wildlife Refuge is a US National Wildlife Refuge located in the southern part of San Francisco Bay, California...
(SFBNWR) (1972). The Bay is also invaded by non-native species.
Tellingly, much of the SFBNWR consists of
saltA salt, in chemistry, is an ionic compound, and can result from the neutralization reaction of acids and bases. Salts are ionic compounds composed of cations and anions so that the product is electrically neutral...
evaporationEvaporation is the vaporization of a liquid and the reverse, of condensation. A type of phase transition, it is the process by which molecules in a liquid state spontaneously become gaseous . Generally, evaporation can be seen by the gradual disappearance of a liquid from a substance when exposed...
ponds purchased or leased from Leslie Salt Company and its successor,
Cargill CorporationCargill, Incorporated is a privately held, multinational corporation, and is based in the state of Minnesota in the United States. It was founded in 1865, and has grown into the country's largest privately held corporation . Were it a publicly held company, it would rank in the top 10 companies...
. These salt ponds produce salt for a variety of industrial purposes, including
chlorineChlorine Chlorine Chlorine ( , from the Greek word 'χλωρóς' (khlôros, meaning 'pale green'), is the chemical element with atomic number 17 and symbol Cl. It is a halogen, found in the periodic table in group 17 (formerly VII, VIIa, or VIIb). As the chloride ion, which is part of common salt and...
bleach and
plasticPlastic is the general common term for a wide range of synthetic or semisynthetic organic amorphous solid materials suitable for the manufacture of industrial products...
s manufacture, as well as supporting dense populations of
brine shrimpBrine shrimp is the English name of the genus Artemia of aquatic crustaceans. Artemia, the only genus in the family Artemiidae, have evolved little since the Triassic period...
, and therefore serving as feeding areas for waterfowl. In 2003, California and Cargill entered one of the largest private land purchases in American history, with the state and federal governments paying about $200 million for 16,000 acres (65 km²) of salt ponds in the south bay. SFBNWR and state biologists hope to restore some of the recently purchased ponds as
tidalTides are the rises and falls of sea level caused by the combined effect of rotation of the Earth and the gravitation of the Moon and the Sun. The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom.Most coastal areas experience...
wetlands.
The seasonal range of water temperature in the Bay is from about 8 °C (46 °F) to about 23 °C (73 °F).
Humphrey the WhaleHumphrey the Whale is arguably the most widely publicized humpback whale in history, having errantly entered San Francisco Bay twice, departing from his Mexico to Alaska migration. This behavior is not normal for any Humpback whale, and Humphrey became well known on national television and press...
entered San Francisco Bay twice on errant migrations, and was successfully rescued and redirected each time in the late 1980s and early 1990s. This occurred again with Dawn and Delta a mother and calf in 2007.
Industrial, mining, and other uses of
mercuryMercury , also called quicksilver or hydrargyrum , is a chemical element with the symbol Hg and atomic number 80...
have resulted in a widespread distribution in the bay, with uptake in the bay's
phytoplanktonPhytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτον , or "plant", and πλαγκτος , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
and contamination of its sportfish. In November 2007, a ship named
Cosco BusanThe Cosco Busan is the former name of a 901-foot-long container ship at the time that it hit a protective fender of the San Francisco – Oakland Bay Bridge in heavy fog at 8:30 a.m. on November 7, 2007. The allision sliced open two fuel tanks and led to the environmentally devastating Cosco Busan...
collided with the San Francisco – Oakland Bay Bridge and spilled over 58,000 gallons of bunker fuel, creating the largest
oil spillAn oil spill is the release of a liquid petroleum hydrocarbon into the environment due to human activity, and is a form of pollution. The term often refers to marine oil spills, where oil is released into the ocean or coastal waters...
in the region since 1996.
At times, San Francisco Bay is covered in a unique
fogThe famous fog of San Francisco, California is a specific case of sea fog. Sea fog is a specific type of advection fog, which is characterized by the lateral transfer of temperature by wind blowing over cooler water. The water is often cool enough to lower the temperature of the air to the...
.
Bay fill and depth profile
San Francisco Bay's profile changed dramatically in the late nineteenth century and again with the initiation of dredging by the US Army Corps of Engineers in the twentieth century. Before about 1860, most bay shores (exception: rocky shores such as those in Carquinez Strait, along Marin shoreline, Point Richmond, Golden Gate area) contained extensive wetlands that graded nearly invisibly from freshwater wetlands to salt marsh and then tidal mudflat. A deep channel ran through the center of the bay, following the ancient drowned river valley.
In the 1860s and continuing into the early twentieth century, miners dumped staggering quantities of mud and gravel from
hydraulic miningHydraulic mining, or hydraulicking, is a form of mining that employs water to dislodge rock material or move sediment. Previously, the use of a large volume of water had been developed by the Romans to remove overburden and then gold-bearing debris as in Las Médulas of Spain, and Dolaucothi in...
operations into the upper Sacramento and San Joaquin Rivers. GK Gilbert's estimates of debris total more than eight times the amount of rock and dirt moved during construction of the Panama Canal. This material flowed down the rivers, progressively eroding into finer and finer sediment, until it reached the bay system. Here some of it settled, eventually filling in Suisun Bay, San Pablo Bay, and San Francisco Bay, in decreasing order of severity.
By the end of the nineteenth century, these "slickens" had filled in much of the shallow bay flats, raising the entire bay profile. New marshes were created in some areas.
In the last years of the nineteenth and first decades of the twentieth century, at the behest of local political officials and following Congressional orders, the US Army Corps began dredging the Sacramento and San Joaquin Rivers and the deep channels of San Francisco Bay. This work has continued without interruption ever since, an enormous federal subsidy of San Francisco Bay shipping. Some of the dredge spoils were initially dumped in the bay shallows (including helping to create "
Treasure IslandTreasure Island is an artificial island in the San Francisco Bay between San Francisco and Oakland. It is connected by a small isthmus to Yerba Buena Island. It was created in 1936 & 1937, from fill dredged from the bay, for the Golden Gate International Exposition...
" on the former shoals to the north of
Yerba Buena IslandYerba Buena Island sits in the San Francisco Bay between San Francisco and Oakland, California. The Yerba Buena Tunnel runs through its center and connects the western and eastern spans of the San Francisco-Oakland Bay Bridge. It has had several other names over the decades: Sea Bird Island, Wood...
) and used to raise an island in the Sacramento-San Joaquin Delta. The net effect of dredging has been to maintain a narrow deep channel - deeper perhaps than the original bay channel - through a much shallower bay. At the same time, most of the marsh areas have been filled or blocked off from the bay by dikes.
Transportation
San Francisco Bay was traversed by watercraft since before the coming of Europeans; the indigenous peoples used their canoes to fish and clam along the shoreline. The era of sail brought ships which communicated with the rest of the world as well as serving as early 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 vessels starting in the late 19th century. Several shipyards were early established around the Bay, augmented during wartime. (
See e.g. Kaiser ShipyardsThe Kaiser Shipyards were seven major shipbuilding yards located on the U.S. west coast during World War II. They were owned by the Kaiser Shipbuilding Company, a creation of American industrialist Henry J...
)
San Francisco Bay is spanned by six bridges, five of them dedicated to vehicle traffic: the
Golden Gate BridgeThe Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the opening of the San Francisco Bay into the Pacific Ocean. As part of both U.S...
(which was the largest single span
suspension bridgeA suspension bridge is a type of bridge in which the deck is hung below suspension cables on vertical suspenders. While modern bridges of this type date from the early 19th century, earlier bridges without vertical suspenders date from the 7th Century in Central America.This type of bridge has...
ever built at the time of its construction), the
Richmond-San Rafael BridgeThe Richmond – San Rafael Bridge is the northernmost of the east–west crossings of the San Francisco Bay in California, USA, connecting Richmond on the east to San Rafael on the west end. It is commonly known as the Richmond Bridge, though in Richmond it is called the San Rafael Bridge...
, the San Francisco – Oakland Bay Bridge, the Hayward-San Mateo Bridge, and the
Dumbarton BridgeThe Dumbarton Bridge is the southernmost of the highway bridges that span the San Francisco Bay in California. Carrying over 81,000 vehicles daily, it is also the shortest bridge across San Francisco Bay at 1.63 miles...
. The sixth is the currently unused railroad bridge just south of the Dumbarton Bridge. The bay is also spanned by the
Transbay TubeThe Transbay Tube is the part of BART which runs under San Francisco Bay in California. The tube is 3.6 miles long; including approaches from the nearest stations , it totals 6 miles...
, an underwater tunnel through which
BARTBay Area Rapid Transit is a rapid transit system serving the San Francisco Bay Area. The heavy-rail public transit system connects San Francisco with cities in the East Bay and suburbs in northern San Mateo County. BART operates five lines on of track with 43 stations in four counties...
runs. Prior to the construction of these infrastructures, transbay transportation was dominated by fleets of
ferryboatsSan Francisco Bay in California has been served by ferries of all types for over 150 years. Although the construction of the Golden Gate Bridge and the San Francisco – Oakland Bay Bridge led to the decline in the importance of most ferries, some are still in use today for both commuters and...
operated by the
Southern Pacific RailroadThe Southern Pacific Transportation Company , earlier Southern Pacific Railroad and Southern Pacific Company , and usually simply called the Southern Pacific, was an American railroad. The railroad was founded as a land holding company in 1865, later acquiring the Central Pacific Railroad by lease...
and the
Key SystemThe Key System was a privately owned company which provided mass transit in the cities of Oakland, Berkeley, Alameda, Emeryville, Piedmont, San Leandro, Richmond, Albany and El Cerrito in the eastern San Francisco Bay Area from 1903 until 1960, when the system was sold to a newly formed public...
transit company. However, in recent decades, ferries have returned, primarily serving commuters from Marin County, relieving the traffic bottleneck of the Golden Gate Bridge. (
See article Ferries of San Francisco BaySan Francisco Bay in California has been served by ferries of all types for over 150 years. Although the construction of the Golden Gate Bridge and the San Francisco – Oakland Bay Bridge led to the decline in the importance of most ferries, some are still in use today for both commuters and...
).
The Bay also continues to serve as a major international shipping port, served by a large container facility operated by the
Port of OaklandThe Port of Oakland was the first major port on the Pacific Coast of the United States to build terminals for container ships. It is now the fourth busiest container port in the United States; behind Long Beach, Los Angeles, and Newark...
, and two smaller facilities in Richmond and San Francisco.
Recreation
San Francisco Bay is a mecca for sailors (boats, as well as windsurfing and kitesurfing), due to consistent strong westerly/northwesterly thermally-generated winds (
Beaufort forceThe Beaufort scale is an empirical measure for describing wind speed based mainly on observed sea conditions. Its full name is the Beaufort wind force scale.-History:...
6 (15-25 knots) is common on summer afternoons) and protection from large open ocean swells.
YachtingYachting refers to recreational sailing or boating, the specific act of sailing or using other vessels for sporting.-Competitive Sailing:...
and
yacht racingYacht racing is the sport of competitive yachting. There is a broad variety of kinds of races and sailboats used for racing. Much racing is done around buoys or similar marks in protected waters, while some longer offshore races cross open water...
are popular pastimes and the San Francisco Bay Area is home to many of the world's top sailors.
Kite boarding and wind surfing are also popular in the bay.
See also
- Islands of San Francisco Bay
This is a list of San Francisco Bay Area islands.-San Francisco Bay:* Alameda Island** Ballena Bay* Alcatraz Island* Angel Island* Bair Island, Redwood City, California* Bay Farm Island, Alameda County* Belvedere Island, Belvedere, California...
- Golden Gate
The Golden Gate is the North American strait connecting San Francisco Bay to the Pacific Ocean. Since 1937 it has been spanned by the Golden Gate Bridge...
- Mount Tamalpais State Park
Mount Tamalpais is a peak in Marin County, California, United States, often considered symbolic of Marin County...
- Mount Diablo State Park
- Napa Sonoma Marsh
The Napa Sonoma Marsh is a wetland at the northern edge of San Pablo Bay, which is a northern arm of the San Francisco Bay in California, USA. This marsh has an area of 48,000 acres , of which 13,000 acres are abandoned salt evaporation ponds...
- Pelagic Ecology of the Low Salinity San Francisco Estuary
Pelagic organisms spend all or part of their lives in the open water, where habitat is defined not by edges but by physiological tolerance to salinity and temperature. The Low Salinity Zone of the San Francisco Estuary constitutes a habitat for a suite of organisms that are specialized to survive...
- Point Pinole Regional Shoreline
The Point Pinole Regional Shoreline is a regional park on the shores of the San Pablo Bay, California . It is approximately s) in area, and is operated by the East Bay Regional Park District....
, Richmond
- Eastshore State Park
Eastshore State Park is a state park and wildlife refuge along the San Francisco Bay shoreline of the East Bay between Richmond, Berkeley, and Oakland. It encompasses remnant natural wetlands, restored wetlands as well as landfill west of the Eastshore Freeway. It is long...
- Hydrography of the San Francisco Bay Area
The Hydrography of the San Francisco Bay Area is a complex network of watersheds, marshes, rivers, creeks, reservoirs, and bays predominantly draining into the San Francisco Bay and Pacific Ocean.-Bays:...
External links