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128-502: The Midpeninsula Regional Open Space District (MROSD) is a non-enterprise special district in the San Francisco Bay Area . Formed in 1972 by voter initiative, it has acquired and preserved a regional green belt of open space land and provides opportunities for ecologically-sensitive public enjoyment and education. The district, which includes parts of Santa Clara , San Mateo and Santa Cruz counties, works to form

256-778: A World Series game between two Bay Area baseball teams, the Loma Prieta earthquake struck and caused widespread infrastructural damage, including the failure of the Bay Bridge , a major link between San Francisco and Oakland . Even so, the Bay Area's technology industry continued to expand and growth in Silicon Valley accelerated: the United States census confirmed that year that San Jose had overtaken San Francisco in terms of population. The commercialization of

384-453: A complex multimodal transportation network. The earliest archaeological evidence of human settlements in the Bay Area dates back to 8000–10,000 BC. The oral tradition of the Ohlone and Miwok people suggests they have been living in the Bay Area for several hundreds if not thousands of years. The Spanish empire claimed the area beginning in the early period of Spanish colonization of

512-739: A continuous green belt of permanently preserved open space by linking its lands with other public park lands. A member of the Bay Area Open Space Council , the district also participates in cooperative efforts such as the San Francisco Bay Trail , Bay Area Ridge Trail , and Skyline-to-the-Sea Trail , which are regional trail systems in the Bay Area that include district lands. The Midpeninsula Regional Open Space District has permanently preserved almost 63,500 acres (25,700 ha) of mountainous, foothill, and bayland open space , creating 26 open space preserves. Of

640-643: A few years earlier, which now provides drinking water for 2.4 million people in the Bay Area. By 1915, the city had been sufficiently rebuilt and advertised itself to the world during the Panama Pacific Exposition that year, although the effects of the quake hastened the loss of the region's dominant status in California to the Los Angeles metropolitan area . During the 1929 stock market crash and subsequent economic depression , not

768-559: A first in the United States, and four years later a majority of voters in the Bay Area rejected California Proposition 8 , which sought to constitutionally restrict marriage to opposite-sex couples but ultimately passed statewide. The Bay Area was also the center of contentious protests concerning racial and economic inequality . In 2009, an African-American man named Oscar Grant was fatally shot by Bay Area Rapid Transit police officers , precipitating widespread protests across

896-573: A harsh environment for organisms. Sediment often settles in intertidal mudflats which are extremely difficult to colonize. No points of attachment exist for algae , so vegetation based habitat is not established. Sediment can also clog feeding and respiratory structures of species, and special adaptations exist within mudflat species to cope with this problem. Lastly, dissolved oxygen variation can cause problems for life forms. Nutrient-rich sediment from human-made sources can promote primary production life cycles, perhaps leading to eventual decay removing

1024-755: A major domestic military and naval hub, with large shipyards constructed in Sausalito and across the East Bay to build ships for the war effort. The Army's San Francisco Port of Embarkation was the primary origin for Army forces shipping out to the Pacific Theater of Operations . That command consisted of fourteen installations including Fort Mason, the Oakland Army Base , Camp Stoneman and Fort McDowell in San Francisco Bay and

1152-529: A number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff; however the freshwater inflow may not be perennial, the connection to the sea may be closed for part of the year and tidal influence may be negligible". This broad definition also includes fjords , lagoons , river mouths , and tidal creeks . An estuary

1280-474: A rate of one thousand per week on their way to California's interior, including the first large influx of Chinese immigrants to the U.S. The rush was so great that vessels were abandoned by the hundreds in San Francisco's ports as crews rushed to the goldfields. The unprecedented influx of new arrivals spread the nascent government authorities thin, and the military was unable to prevent desertions. As

1408-422: A regional greenbelt of open space land in perpetuity; protect and restore the natural environment; and provide opportunities for ecologically sensitive public enjoyment and education. Most of the preserves are open to recreation . Popular activities are hiking , cycling , and horseback riding . Paragliding and hang gliding are permitted at Windy Hill Open Space Preserve with a special use permit. Camping

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1536-466: A result, numerous vigilante groups formed to provide order, but many tasked themselves with forcibly moving or killing local Native Americans , and by the end of the Gold Rush, two thirds of the indigenous population had been killed. During this same time, a constitutional convention was called to determine California's application for statehood into the United States. After statehood was granted,

1664-499: A significant earthquake hazard. Among the more well-understood faults, as of 2014, scientists estimate a 72% probability of a magnitude 6.7 earthquake occurring along either the Hayward, Rogers Creek, or San Andreas fault, with an earthquake more likely to occur in the East Bay's Hayward Fault. Two of the largest earthquakes in recent history were the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake . The Bay Area

1792-535: A single San Francisco-based bank failed, while the region attempted to spur job growth by simultaneously undertaking two large infrastructure projects: construction of the Golden Gate Bridge , which would connect San Francisco with Marin County , and the Bay Bridge , which would connect San Francisco with Oakland and the East Bay. After the United States joined World War II in 1941, the Bay Area became

1920-622: A single county, Alameda. Diverse assemblages adjoin in complex arrangements due to offsets along the many faults (both active and stable) in the area. As a consequence, many types of rock and soil are found in the region. The oldest rocks are metamorphic rocks that are associated with granite in the Salinian Block west of the San Andreas Fault . These were formed from sedimentary rocks of sandstone , limestone , and shale in uplifted seabeds. Volcanic deposits also exist in

2048-410: A stampede of wealth-seekers descending on Sutter's Mill . The Bay Area's population quickly emptied out as laborers, clerks, waiters, and servants joined the rush to find gold, and California's first newspaper, The Californian , was forced to announce a temporary freeze in new issues due to labor shortages. By the end of 1849, news had spread across the world and newcomers flooded into the Bay Area at

2176-675: A storm sank the San Agustin and killed between 7 and 12 people. On December 8, 80 remaining crew members set sail on the San Buenaventura , a launch which was partially constructed en route from the Philippines . Seeking the fastest route south, the expedition sailed past the Golden Gate, arriving at Puerto de Chacala, Mexico on January 17, 1596. The Bay Area estuaries remained unknown to Europeans until members of

2304-408: A type of ecosystem in some estuaries that have been negatively impacted by eutrophication. Cordgrass vegetation dominates the salt marsh landscape. Excess nutrients allow the plants to grow at greater rates in above ground biomass, however less energy is allocated to the roots since nutrients is abundant. This leads to a lower biomass in the vegetation below ground which destabilizes the banks of

2432-563: A well-mixed water column and the disappearance of the vertical salinity gradient . The freshwater-seawater boundary is eliminated due to the intense turbulent mixing and eddy effects . The lower reaches of Delaware Bay and the Raritan River in New Jersey are examples of vertically homogeneous estuaries. Inverse estuaries occur in dry climates where evaporation greatly exceeds the inflow of freshwater. A salinity maximum zone

2560-436: A wholly marine embayment to any of the other estuary types. The most important variable characteristics of estuary water are the concentration of dissolved oxygen, salinity and sediment load. There is extreme spatial variability in salinity, with a range of near-zero at the tidal limit of tributary rivers to 3.4% at the estuary mouth. At any one point, the salinity will vary considerably over time and seasons, making it

2688-414: A wide effect on the surrounding water bodies.  In turn, this can decrease fishing industry sales in one area and across the country. Production in 2016 from recreational and commercial fishing contributes billions of dollars to the United States' gross domestic product (GDP). A decrease in production within this industry can affect any of the 1.7 million people the fishing industry employs yearly across

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2816-455: Is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides . The effects of tides on estuaries can show nonlinear effects on the movement of water which can have important impacts on the ecosystem and waterflow. The seawater entering the estuary is diluted by the fresh water flowing from rivers and streams. The pattern of dilution varies between different estuaries and depends on

2944-787: Is accepted by most local governmental agencies including San Francisco Regional Water Quality Control Board , Bay Area Air Quality Management District , the San Francisco Bay Restoration Authority , the Metropolitan Transportation Commission , and the Association of Bay Area Governments , the latter two of which partner to deliver a Bay Area Census using the nine-county definition. Various U.S. Federal government agencies use definitions that differ from their local counterparts' nine-county definition. For example,

3072-403: Is additionally known for the complexity of its landforms, the result of millions of years of tectonic plate movements. Because the Bay Area is crossed by six major earthquake faults , the region is particularly exposed to hazards presented by large earthquakes. The climate is temperate and conducive to outdoor recreational and athletic activities such as hiking, running, and cycling. The Bay Area

3200-513: Is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus , meaning tide. There have been many definitions proposed to describe an estuary. The most widely accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which seawater is measurably diluted with freshwater derived from land drainage". However, this definition excludes

3328-411: Is formed, and both riverine and oceanic water flow close to the surface towards this zone. This water is pushed downward and spreads along the bottom in both the seaward and landward direction. Examples of an inverse estuary are Spencer Gulf , South Australia, Saloum River and Casamance River , Senegal. Estuary type varies dramatically depending on freshwater input, and is capable of changing from

3456-623: Is generally prohibited, though the Monte Bello Open Space Preserve does have a backpacking camp available by permit only. Of the 26 preserves, 24 are fully open to the public: Miramontes Ridge Open Space Preserve and Tunitas Creek Open Space Preserve are not open; the Bear Creek Redwoods Open Space Preserve and La Honda Creek Open Space Preserve require a permit for use, and portions of Sierra Azul Open Space Preserve are closed to

3584-867: Is home to a complex network of watersheds, marshes, rivers, creeks, reservoirs, and bays that predominantly drain into the San Francisco Bay and Pacific Ocean. The largest bodies of water in the Bay Area are the San Francisco , San Pablo , and Suisun estuaries. Major rivers of the North Bay include the Napa River , the Petaluma River , the Gualala River , and the Russian River ; the former two drain into San Pablo Bay ,

3712-474: Is host to five professional sports teams and is a cultural center for music, theater, and the arts. It is also host to numerous higher education institutions, including research universities such as the University of California, Berkeley , and Stanford University , the latter known for helping to create the high tech center called Silicon Valley . Home to 101 municipalities and 9 counties, governance in

3840-468: Is largely influenced by the cold California Current , which penetrates the natural mountainous barrier along the coast by traveling through various gaps. In terms of precipitation , this means that the Bay Area has pronounced seasons. The winter season, which roughly runs between November and March, is the source of about 82% of annual precipitation in the area. In the South Bay and further inland, while

3968-566: Is less restricted, and there is a slow but steady exchange of water between the estuary and the ocean. Fjord-type estuaries can be found along the coasts of Alaska , the Puget Sound region of western Washington state , British Columbia , eastern Canada, Greenland , Iceland , New Zealand, and Norway. These estuaries are formed by subsidence or land cut off from the ocean by land movement associated with faulting , volcanoes , and landslides . Inundation from eustatic sea-level rise during

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4096-646: Is the whitefish species from the European Alps . Eutrophication reduced the oxygen levels in their habitats so greatly that whitefish eggs could not survive, causing local extinctions. However, some animals, such as carnivorous fish, tend to do well in nutrient-enriched environments and can benefit from eutrophication. This can be seen in populations of bass or pikes. Eutrophication can affect many marine habitats which can lead to economic consequences. The commercial fishing industry relies upon estuaries for approximately 68 percent of their catch by value because of

4224-604: The Bank of Italy (now known as the Bank of America ), had managed to retrieve the money from his bank's vaults before fires broke out through the city and was the only bank with liquid funds readily available and was instrumental in loaning out funds for rebuilding efforts. Congress immediately approved plans for a reservoir in Hetch Hetchy Valley in Yosemite National Park , a plan they had denied

4352-559: The Bay Area , is a region of California surrounding and including San Francisco Bay . The Association of Bay Area Governments defines the Bay Area as including the nine counties that border the estuaries of San Francisco Bay, San Pablo Bay , and Suisun Bay : Alameda , Contra Costa , Marin , Napa , San Mateo , Santa Clara , Solano , Sonoma , and San Francisco . Other definitions may be either smaller or larger, and may include neighboring counties which are not officially part of

4480-624: The Federal Communications Commission (FCC) which regulates broadcast, cable, and satellite transmissions, includes nearby Colusa , Lake and Mendocino counties in their " San Francisco - Oakland - San Jose " media market , but excludes eastern Solano County. On the other hand, the United States Office of Management and Budget , which designates metropolitan statistical areas (MSAs) and combined statistical areas (CSA) for populated regions across

4608-597: The Golden Gate or the estuaries, likely due to fog. Sir Francis Drake became the first European to land in the area and claim it in June 1579, when he landed at Drakes Bay near Point Reyes. Even though he claimed the region for Queen Elizabeth I as Nova Albion or New Albion , the English made no immediate follow up to the claim. In 1595, Philip II of Spain tasked Sebastião Rodrigues Soromenho with mapping

4736-711: The Hayward Fault Zone , Concord-Green Valley Fault , Calaveras Fault , Clayton-Marsh Creek-Greenville Fault , Rodgers Creek Fault , and the San Gregorio Fault . Significant blind thrust faults (faults with near vertical motion and no surface ruptures) are associated with portions of the Santa Cruz Mountains and the northern reaches of the Diablo Range and Mount Diablo . These "hidden" faults, which are not as well known, pose

4864-662: The Hayward fault , and the Diablo Range , which includes Mount Diablo and Mount Hamilton and runs along the Calaveras fault . In total, the Bay Area is traversed by seven major fault systems with hundreds of related faults, all of which are stressed by the relative motion between the Pacific Plate and the North American Plate or by compressive stresses between these plates. The fault systems include

4992-614: The Holocene Epoch has also contributed to the formation of these estuaries. There are only a small number of tectonically produced estuaries; one example is the San Francisco Bay , which was formed by the crustal movements of the San Andreas Fault system causing the inundation of the lower reaches of the Sacramento and San Joaquin rivers . In this type of estuary, river output greatly exceeds marine input and tidal effects have minor importance. Freshwater floats on top of

5120-516: The Internet in the middle of the decade rapidly created a speculative bubble in the high-tech economy known as the dot-com bubble . This bubble began collapsing in the early 2000s and the industry continued contracting for the next few years, nearly wiping out the market. Companies like Amazon.com and Google managed to weather the crash however, and following the industry's return to normalcy, their market value increased significantly. Even as

5248-610: The Mandovi estuary in Goa during the monsoon period. As tidal forcing increases, river output becomes less than the marine input. Here, current induced turbulence causes mixing of the whole water column such that salinity varies more longitudinally rather than vertically, leading to a moderately stratified condition. Examples include the Chesapeake Bay and Narragansett Bay . Tidal mixing forces exceed river output, resulting in

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5376-640: The Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast . Bar-built estuaries are found in a place where the deposition of sediment has kept pace with rising sea levels so that the estuaries are shallow and separated from the sea by sand spits or barrier islands. They are relatively common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches ( barrier islands and barrier spits ). Formation of barrier beaches partially encloses

5504-619: The North Pacific High through the Golden Gate, which creates the city's characteristic cool winds and fog . The microclimate phenomenon is most pronounced during this time, when fog penetration is at its maximum in areas near the Golden Gate strait, while the South Bay and areas further inland are sunny and dry. Along the San Francisco peninsula, gaps in the Santa Cruz Mountains , one south of San Bruno Mountain and another in Crystal Springs, allow oceanic weather into

5632-556: The Pacific Ocean on the west and the bay on the east and are characterized by their mountainous and woody terrain. Sonoma and Napa counties are known internationally for their grape vineyards and wineries , and Solano County to the east, centered around Vallejo , is the fastest growing region in the Bay Area. The " Peninsula " subregion includes the cities and towns on the San Francisco Peninsula, excluding

5760-615: The Portolá expedition , while trekking along the California coast, encountered them in 1769 when the Golden Gate blocked their continued journey north. Several missions were founded in the Bay Area during this period. In 1806, a Spanish expedition led by Gabriel Moraga began at the Presidio, traveled south of the bay, and then east to explore the San Joaquin Valley . In 1821, Mexico gained its independence from Spain and

5888-604: The San Joaquin River Delta , causing a cooling effect in Stockton and Sacramento , so that these cities are also cooler than their Central Valley counterparts in the south. The Bay Area is home to a diverse array of wildlife and, along with the connected San Joaquin River Delta represents one of California's most important ecological habitats. California's Dungeness crab , Pacific halibut , and

6016-734: The Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross-section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River , Chesapeake Bay , and Delaware Bay along

6144-684: The USS ; Portsmouth into the bay and seized San Francisco, which was then known as Yerba Buena , and raised the American flag for the first time over Portsmouth Square . In 1848, James W. Marshall 's discovery of gold in the American River sparked the California Gold Rush , and within half a year 4,000 men were panning for gold along the river and finding $ 50,000 per day. The promise of fabulous riches quickly led to

6272-615: The University of California, Berkeley Richard Walker claimed that "no other U.S. city-region is as definitionally challenged [as the Bay Area]." When the region began to rapidly develop during and immediately after World War II , local planners settled on a nine-county definition for the Bay Area, consisting of the counties that directly border the San Francisco , San Pablo , and Suisun estuaries : Alameda , Contra Costa , Marin , Napa , San Francisco , San Mateo , Santa Clara , Solano , and Sonoma counties. Today, this definition

6400-478: The black-tailed godwit , rely on estuaries. Two of the main challenges of estuarine life are the variability in salinity and sedimentation . Many species of fish and invertebrates have various methods to control or conform to the shifts in salt concentrations and are termed osmoconformers and osmoregulators . Many animals also burrow to avoid predation and to live in a more stable sedimental environment. However, large numbers of bacteria are found within

6528-485: The gay rights movement . At the same time, parts of San Mateo and Santa Clara counties began to rapidly develop from an agrarian economy into a hotbed of the high-tech industry . Fred Terman , the director of a top-secret research project at Harvard University during World War II, joined the faculty at Stanford University in order to reshape the university's engineering department. His students, including David Packard and William Hewlett , would later help usher in

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6656-476: The osprey . In 1927, zoologist Joseph Grinnell wrote that osprey were only rare visitors to the San Francisco Bay Area, although he noted records of one or two used nests in the broken tops of redwood trees along the Russian River . In 1989, the southern breeding range of the osprey in the Bay Area was Kent Lake , although osprey were noted to be extending their range further south in

6784-575: The west coast of the United States , including populations residing in tributaries to San Francisco Bay. California Coast Chinook salmon were historically native to the Guadalupe River in San Francisco Bay, and Chinook salmon runs persist today in the Guadalupe River, Coyote Creek , Napa River , and Walnut Creek . Industrial, mining, and other uses of mercury have resulted in a widespread distribution of that poisonous metal in

6912-587: The 1980s an effort to re-introduce the species to the area began with the Santa Cruz Predatory Bird Research Group and the San Francisco Zoo importing birds and eggs from Vancouver Island and northeastern California, and there are now nineteen nesting couples in eight of the Bay Area's nine counties. Other once absent species that have returned to the Bay Area include Swainson's hawk , white tailed kite , and

7040-550: The Americas . The earliest Spanish exploration of the Bay Area took place in 1769. The Mexican government controlled the area from 1821 until the 1848 Treaty of Guadalupe Hidalgo . Also in 1848, James W. Marshall discovered gold in nearby mountains , resulting in explosive immigration to the area and the precipitous decline of the Native population . The California Gold Rush brought rapid growth to San Francisco . California

7168-416: The Bay Area at the time of first European contact were descended from Siberian tribes who arrived at around 1,000 BCE by sailing over the Arctic Ocean and following the salmon migration. However the current academic consensus is compatible with the oral tradition of the Ohlone and Miwok peoples, which suggests they have been living in the Bay Area for several hundreds if not thousands of years. At

7296-439: The Bay Area became part of the Mexican province of Alta California , a period characterized by ranch life and visiting American trappers. Mexico's control of the territory would be short-lived, however, and in 1846 a party of settlers occupied Sonoma Plaza and proclaimed the independence of the new Republic of California . That same year, the Mexican–American War began, and American captain John Berrien Montgomery sailed

7424-449: The Bay Area has experienced numerous political, cultural, and artistic movements, developing unique local genres in music and art and establishing itself as a hotbed of progressive politics . Economically, the post-war Bay Area saw large growth in the financial and technology industries, creating an economy with a gross domestic product of over $ 700 billion. In 2018 it was home to the third-highest concentration of Fortune 500 companies in

7552-402: The Bay Area involves numerous local and regional jurisdictions, often with broad and overlapping responsibilities. The Coyote Hills Shell Mound, the earliest known archaeological evidence of human habitation of the Bay Area estuaries, dates to around 10,000 BCE, with evidence pointing to even earlier settlement in Point Reyes in Marin County . It has been conjectured that the people living in

7680-509: The Bay Area their home, making the region a popular destination for birdwatching . Many birds are listed as endangered species despite once being common in the region. Western burrowing owls were originally listed as a species of special concern by the California Department of Fish and Game in 1979. California's population declined 60% from the 1980s to the early 1990s, and continues to decline at roughly 8% per year. A 1992–93 survey reported little to no breeding burrowing owls in most of

7808-434: The Bay Area, all naturally spawned anadromous steelhead populations below natural and manmade impassable barriers in California streams from the Russian River to Aptos Creek , and the drainages of San Francisco, San Pablo, and Suisun Bays are listed as threatened under the Federal Endangered Species Act . The Central California Coast coho salmon population is the most endangered of the many troubled salmon populations on

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7936-420: The Bay Area, left behind by the movement of the San Andreas Fault, whose movement sliced a subduction plate and allowed magma to briefly flow to the surface. The region has considerable vertical relief in its landscapes that are not in the alluvial plains leading to the bay or in the inland valleys. The topography, and geologic history, of the Bay Area can largely be attributed to the compressive forces between

8064-420: The Bay Area: the Karkin of the Carquinez Strait , the Chochenyo of the East Bay , the Ramaytush of the San Francisco Peninsula , and the Tamien of the South Bay. The Miwok had two major groups in the Bay Area: the Bay Miwok of Contra Costa and the Coast Miwok of Marin and Sonoma . In 1542, Juan Rodríguez Cabrillo explored the Pacific coast near the Bay Area though the expedition did not see

8192-458: The Bay. The wild turkey population was introduced in the 1960s by state game officials, and by 2015 have become a common sight in East Bay communities. The Bay Area is well known for the complexity of its landforms that are the result of the forces of plate tectonics acting over of millions of years, since the region is located in the middle of a meeting point between two plates. Nine out of eleven distinct assemblages have been identified in

8320-424: The California scorpionfish are all significant components of the bay's fisheries . The bay's salt marshes now represent most of California's remaining salt marsh and support a number of endangered species and provide key ecosystem services such as filtering pollutants and sediments from the rivers. Most famously, the bay is a key link in the Pacific Flyway and with millions of shorebirds annually visiting

8448-554: The Central Valley and the Sierra Nevada. In 2014, a Bay Area-wide survey found osprey had extended their breeding range southward with nesting sites as far south as Hunters Point in San Francisco on the west side and Hayward on the east side, while further studies have found nesting sites as far south as the Los Gatos Creek watershed, indicating that the nesting range now includes the entire length of San Francisco Bay. Most nests were built on man-made structures close to areas of human disturbance, likely due to lack of mature trees near

8576-408: The East Bay receives oceanic weather that travels through the Golden Gate strait, and further diffuses that air through the Berkeley Hills , Niles Canyon and the Hayward Pass into the Livermore Valley and Altamont Pass . Here, the resulting breeze is so strong that it is home to one of the world's largest array of wind turbines . Further north, the Carquinez Strait funnels the ocean weather into

8704-434: The Pacific Plate and the North American plate. The three major ridge structures in the Bay Area, part of the Pacific Coast Range , are all roughly parallel to the major faults . The Santa Cruz Mountains along the San Francisco Peninsula and the Marin Hills in Marin County follow the San Andreas fault , The Berkeley Hills , San Leandro Hills and their southern ridgeline extension through Mission Peak roughly follow

8832-413: The San Francisco Bay Area are not officially delineated, and the unique development patterns influenced by the region's topography , as well as unusual commute patterns caused by the presence of three central cities and employment centers located in various suburban locales, has led to considerable disagreement between local and federal definitions of the area. Because of this, professor of geography at

8960-415: The San Francisco Bay Area, such as the Central Coast counties of Santa Cruz , San Benito , and Monterey , or the Central Valley counties of San Joaquin , Merced , and Stanislaus . The Bay Area is known for its natural beauty, prominent universities, technology companies, and affluence. The Bay Area contains many cities, towns, airports, and associated regional, state, and national parks, connected by

9088-411: The United States. The Bay Area is home to approximately 7.52 million people. The larger federal classification, the combined statistical area of the region which includes 13 counties, is the second-largest in California—after the Greater Los Angeles area—and the fifth-largest in the United States, with over 9 million people. The Bay Area's population is ethnically diverse: roughly three-fifths of

9216-400: The United States. Estuaries are incredibly dynamic systems, where temperature, salinity, turbidity, depth and flow all change daily in response to the tides. This dynamism makes estuaries highly productive habitats, but also make it difficult for many species to survive year-round. As a result, estuaries large and small experience strong seasonal variation in their fish communities. In winter,

9344-488: The Whale , a humpback whale who entered San Francisco Bay twice on errant migrations in the late 1980s and early 1990s. Bottlenose dolphins and harbor porpoises have recently returned to the bay, having been absent for many decades. Historically, this was the northern extent of their warm-water species range. In addition to the many species of marine birds that can be seen in the Bay Area, many other species of birds make

9472-513: The above definition of an estuary and could be fully saline. Many estuaries suffer degeneration from a variety of factors including soil erosion , deforestation , overgrazing , overfishing and the filling of wetlands. Eutrophication may lead to excessive nutrients from sewage and animal wastes; pollutants including heavy metals , polychlorinated biphenyls , radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion. The word "estuary"

9600-472: The area's largest city and the 13th-most populous in the United States . Despite its urban character, San Francisco Bay is one of California's most ecologically sensitive habitats, providing important ecosystem services such as filtering the pollutants and sediments from rivers and supporting a number of endangered species . In addition, the Bay Area is known for its stands of coast redwoods , many of which are protected in state and county parks. The region

9728-590: The bay has been significantly altered heavily re-engineered to accommodate the needs of water delivery, shipping, agriculture, and urban development, with side effects including the loss of wetlands and the introduction of contaminants and invasive species . Approximately 85% of those marshes have been lost or destroyed, but about 50 marshes and marsh fragments remain. Huge tracts of the marshes were originally destroyed by farmers for agricultural purposes, then repurposed to serve as salt evaporation ponds to produce salt for food and other purposes. Today, regulations limit

9856-436: The bay into north and south regions. In 1989, the federal Environmental Protection Agency defined the South Bay as the northern part of Santa Clara County and the southeastern part of San Mateo County. The Bay Area is located in the warm-summer Mediterranean climate zone ( Köppen Csb ) that is a characteristic of California's coast, featuring mild to cool winters with occasional rainfall, and warm to hot, dry summers. It

9984-502: The bay shallows as a refuge, is the most important component of the flyway south of Alaska . Many endangered species of birds are also found here: the California least tern , the California clapper rail , the snowy egret , and the black crowned night heron . There is also a significant diversity of salmonids present in the bay. Steelhead populations in California have dramatically declined due to human and natural causes; in

10112-488: The bay, with uptake in the bay's phytoplankton and contamination of its sportfish . Aquatic mammals are also present in the bay. Before 1825, Spanish, French, English, Russians and Americans were drawn to the Bay Area to harvest prodigious quantities of beaver , river otter , marten, fisher, mink, fox, weasel, harbor and fur seals and sea otter . This early fur trade, known as the California Fur Rush ,

10240-452: The bottom where they are harmless. Historically the oysters filtered the estuary's entire water volume of excess nutrients every three or four days. Today that process takes almost a year, and sediment, nutrients, and algae can cause problems in local waters. Some major rivers that run through deserts historically had vast, expansive estuaries that have been reduced to a fraction of their former size, because of dams and diversions. One example

10368-489: The capital city moved between three cities in the Bay Area: San Jose (1849–1851), Vallejo (1851–1852), and Benicia (1852–1853) before permanently settling in Sacramento in 1854. As the Gold Rush subsided, wealth generated from the endeavor led to the establishment of Wells Fargo Bank and the Bank of California , and immigrant laborers attracted by the promise of wealth transformed the demographic makeup of

10496-568: The city of San Francisco, natural and artificial topographical features direct the movement of wind and fog, resulting in startlingly varied climates between city blocks. Along the Golden Gate Strait , oceanic wind and fog from the Pacific Ocean are able to penetrate the mountain barriers inland into the Bay Area. During the summer, rising hot air in California's interior valleys creates a low pressure area that draws winds from

10624-494: The country, has five MSAs which include, wholly or partially, areas within the nine-county definition, and one CSA which includes eight Bay Area counties (excluding Sonoma ), but including neighboring San Benito , Santa Cruz , San Joaquin , Merced , and Stanislaus counties. The Association of Bay Area Health Officers (ABAHO), an organization that has fought local outbreaks of HIV/AIDS in 1980s and with COVID-19 pandemic and Delta cron hybrid variant (2020–22), consists of

10752-490: The destruction of tidal marshes, and large portions are currently being rehabilitated to their natural state. Over time, droughts and wildfires have increased in frequency and become less seasonal and more year-round, further straining the region's water security . According to the 2010 United States Census , the population of the nine-county Bay Area was 7.15 million, with 49.6% male and 50.4% female. Of these, approximately 2.3 million (32%) are foreign born. In 2010

10880-409: The dissolved oxygen from the water; thus hypoxic or anoxic zones can develop. Nitrogen is often the lead cause of eutrophication in estuaries in temperate zones. During a eutrophication event, biogeochemical feedback decreases the amount of available silica . These feedbacks also increase the supply of nitrogen and phosphorus, creating conditions where harmful algal blooms can persist. Given

11008-672: The district and provide a range of services. Ranger staff are peace officers but do not carry firearms. They wear tan and green uniforms; the badge is a gold metal seven-point star with an enameled California state seal in the center. Dispatch services are provided by the Mountain View Police Department under contract. The following open space preserves are managed by MROSD: 37°23′47″N 122°06′21″W  /  37.39641°N 122.105922°W  / 37.39641; -122.105922 San Francisco Bay Area The San Francisco Bay Area , commonly known as

11136-622: The district's 26 preserves, 24 are open to the public free of charge, 365 days a year from dawn until one-half hour after sunset. The district's tax and voter base consists of about 550 square miles (1,400 km) and 741,000 people, mostly in Santa Clara and San Mateo counties. District revenues for fiscal year 2012-2013 were $ 33 million, with $ 30.3 million coming directly from a portion of property taxes. The district also occasionally receives state and federal grants, as well as private donations. Its stated mission is: To acquire and preserve

11264-401: The effects of modifying the estuarine circulation. Fjord -type estuaries are formed in deeply eroded valleys formed by glaciers . These U-shaped estuaries typically have steep sides, rock bottoms, and underwater sills contoured by glacial movement. The estuary is shallowest at its mouth, where terminal glacial moraines or rock bars form sills that restrict water flow. In the upper reaches of

11392-601: The estuary impacted by human activities, and over time may shift the basic composition of the ecosystem, and the reversible or irreversible changes in the abiotic and biotic parts of the systems from the bottom up. For example, Chinese and Russian industrial pollution, such as phenols and heavy metals, has devastated fish stocks in the Amur River and damaged its estuary soil. Estuaries tend to be naturally eutrophic because land runoff discharges nutrients into estuaries. With human activities, land run-off also now includes

11520-424: The estuary, the depth can exceed 300 m (1,000 ft). The width-to-depth ratio is generally small. In estuaries with very shallow sills, tidal oscillations only affect the water down to the depth of the sill, and the waters deeper than that may remain stagnant for a very long time, so there is only an occasional exchange of the deep water of the estuary with the ocean. If the sill depth is deep, water circulation

11648-776: The estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries typically develop on gently sloping plains located along tectonically stable edges of continents and marginal sea coasts. They are extensive along the Atlantic and Gulf coasts of the U.S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m (13 ft). The barrier beaches that enclose bar-built estuaries have been developed in several ways: Fjords were formed where Pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross-sections. At their mouths there are typically rocks, bars or sills of glacial deposits , which have

11776-609: The fish community is dominated by hardy marine residents, and in summer a variety of marine and anadromous fishes move into and out of estuaries, capitalizing on their high productivity. Estuaries provide a critical habitat to a variety of species that rely on estuaries for life-cycle completion. Pacific Herring ( Clupea pallasii ) are known to lay their eggs in estuaries and bays, surfperch give birth in estuaries, juvenile flatfish and rockfish migrate to estuaries to rear, and anadromous salmonids and lampreys use estuaries as migration corridors. Also, migratory bird populations, such as

11904-400: The great biodiversity of this ecosystem. During an algal bloom , fishermen have noticed a significant increase in the quantity of fish. A sudden increase in primary productivity causes spikes in fish populations which leads to more oxygen being utilized. It is the continued deoxygenation of the water that then causes a decline in fish populations. These effects can begin in estuaries and have

12032-553: The growth of the technology sector transformed the region's economy, progressive politics continued to guide the region's political environment. By the turn of the millennium, non-Hispanic whites , the largest ethnic group in the United States, were only half of the population in the Bay Area as immigration among minority groups accelerated. During this time, the Bay Area was the center of the LGBT rights movement : in 2004, San Francisco began issuing marriage licenses to same-sex couples ,

12160-581: The hit American pop song San Francisco (Be Sure to Wear Flowers in Your Hair) further enticing like-minded individuals to join the movement in the Bay Area and leading to the Summer of Love . In the proceeding decades, the Bay Area would cement itself as a hotbed of New Left activism, student activism , opposition to the Vietnam War and other anti-war movements , the black power movement , and

12288-420: The impacts do not end there. Plant death alters the entire food web structure which can result in the death of animals within the afflicted biome . Estuaries are hotspots for biodiversity , containing a majority of commercial fish catch, making the impacts of eutrophication that much greater within estuaries. Some specific estuarine animals feel the effects of eutrophication more strongly than others. One example

12416-523: The interior, causing a cooling effect for cities along the Peninsula and even as far south as San Jose. This weather pattern is also the source for delays at San Francisco International Airport . In Marin county north of the Golden Gate strait, two gaps north of Muir Woods bring cold air across the Marin Headlands , with the cooling effect reaching as far north as Santa Rosa . Further inland,

12544-408: The larger subregions, the East Bay includes a variety of enclaves, including the suburban Tri-Valley area and the highly urban western part of the subregion that runs alongside the bay, including Oakland. The " North Bay " includes Marin , Sonoma , Napa , and Solano counties, and is the geographically largest and least populated subregion. The western counties of Marin and Sonoma are encased by

12672-429: The latter two into the Pacific Ocean. In the South Bay, the Guadalupe River drains into San Francisco Bay near Alviso . There are also several lakes present in the Bay Area, including man-made lakes like Lake Berryessa and natural albeit heavily modified lakes like Lake Merritt . Prior to the introduction of European agricultural methods, the shores of San Francisco Bay consisted mostly of tidal marshes. Today,

12800-525: The many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. Excess oxygen-depleting chemicals in the water can lead to hypoxia and the creation of dead zones . This can result in reductions in water quality, fish, and other animal populations. Overfishing also occurs. Chesapeake Bay once had a flourishing oyster population that has been almost wiped out by overfishing. Oysters filter these pollutants, and either eat them or shape them into small packets that are deposited on

12928-422: The marine environment, such as plastics , pesticides , furans , dioxins , phenols and heavy metals . Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation . They also accumulate in benthic environments, such as estuaries and bay muds : a geological record of human activities of the last century. The elemental composition of biofilm reflect areas of

13056-575: The marsh causing increased rates of erosion . A similar phenomenon occurs in mangrove swamps , which are another potential ecosystem in estuaries. An increase in nitrogen causes an increase in shoot growth and a decrease in root growth. Weaker root systems cause a mangrove tree to be less resilient in seasons of drought, which can lead to the death of the mangrove. This shift in above ground and below ground biomass caused by eutrophication could hindered plant success in these ecosystems. Across all biomes, eutrophication often results in plant death but

13184-588: The most ethnically diverse cities in the United States. Estuary Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays , harbors , lagoons , inlets , or sounds , although some of these water bodies do not strictly meet

13312-440: The now off-balance nitrogen cycle , estuaries can be driven to phosphorus limitation instead of nitrogen limitation. Estuaries can be severely impacted by an unbalanced phosphorus cycle, as phosphorus interacts with nitrogen and silica availability. With an abundance of nutrients in the ecosystem, plants and algae overgrow and eventually decompose, which produce a significant amount of carbon dioxide. While releasing CO 2 into

13440-485: The public due to hazardous areas at the summit of Mount Umunhum . In total, the district has 226 mi (364 km) of hiking trails, of which 150 mi (241 km) is open to bicycles, 182 mi (293 km) to equestrians, and 63 mi (101 km) to leashed dogs. Preserves are relatively undeveloped, with most having only a parking area, trail signs, and possibly an outhouse. All preserves are open from dawn to one-half hour after sunset. Park rangers patrol

13568-688: The public health officers of 9 Bay Area counties, in addition to the Central Coast counties of Santa Cruz , San Benito , and Monterey and the city of Berkeley . Among locals, the nine-county Bay Area is divided into five sub-regions: the East Bay , North Bay , Peninsula , city of San Francisco , and South Bay . The " East Bay " is the densest region of the Bay Area outside of San Francisco and includes cities and towns in Alameda and Contra Costa counties centered around Oakland . As one of

13696-497: The racial makeup of the nine-county Bay Area was 52.5% White (42.4% were non-Hispanic and 10.1% were Hispanic ), 23.3% Asian , 6.7% non-Hispanic Black or African American , 0.7% Native American or Alaska Native , 0.6% Pacific Islander , 5.4% from two or more races and 10.8% from other races. Hispanic or Latino residents of any race formed 23.5% of the population. The Bay Area cities of Vallejo , Suisun City , Oakland , San Leandro , Fairfield , and Richmond are among

13824-525: The region and even riots in Oakland. His name was symbolically tied to the Occupy Oakland protests two years later that sought to fight against social and economic inequality. By August 2023, San Francisco was in such severe decline that Mayor Matt Mahan of San Jose joked that one day the region might be renamed the "San Jose Bay Area", after its largest and most prosperous city. The borders of

13952-472: The region's high-tech revolution. In 1955, Shockley Semiconductor Laboratory opened for business in Mountain View near Stanford, and although the business venture was a financial failure, it was the first semiconductor company in the Bay Area, and the talent that it attracted to the region eventually led to a high-tech cluster of companies later known as Silicon Valley . In 1989, in the middle of

14080-412: The region's residents are Hispanic/Latino , Asian , African/Black , Indian , or Pacific Islander , all of whom have a significant presence throughout the region. Most of the remaining two-fifths of the population is non-Hispanic White American . The most populous cities of the Bay Area are San Francisco, Oakland , and San Jose , the latter of which had a population of 969,655 in 2023, making San Jose

14208-563: The region. In the early morning of April 18, 1906, a large earthquake with an epicenter near the city of San Francisco hit the region. Immediate casualty estimates by the U.S. Army 's relief operations were 498 deaths in San Francisco, 64 deaths in Santa Rosa , and 102 in or near San Jose, for a total of about 700. More recent studies estimate the total death count to be over 3,000, with over 28,000 buildings destroyed. Rebuilding efforts began immediately. Amadeo Peter Giannini , owner of

14336-598: The region. Between 1950 and 1960, San Francisco welcomed over 100,000 new residents, inland suburbs in the East Bay saw their populations double, Daly City 's population quadrupled, and Santa Clara 's population quintupled. By the early 1960s, the Bay Area and the rest of Northern California became the center of the counterculture movement . Telegraph Avenue in Berkeley and the Haight-Ashbury neighborhood in San Francisco were seen as centers of activity, with

14464-525: The region. Construction of the First transcontinental railroad from the Oakland Long Wharf attracted so many laborers from China that by 1870, eight percent of San Francisco's population was of Asian origin. The completion of the railroad connected the Bay Area with the rest of the United States, established a truly national marketplace for the trade of goods, and accelerated the urbanization of

14592-427: The seawater in a layer that gradually thins as it moves seaward. The denser seawater moves landward along the bottom of the estuary, forming a wedge-shaped layer that is thinner as it approaches land. As a velocity difference develops between the two layers, shear forces generate internal waves at the interface, mixing the seawater upward with the freshwater. An examples of a salt wedge estuary is Mississippi River and

14720-411: The sediment which has a very high oxygen demand. This reduces the levels of oxygen within the sediment often resulting in partially anoxic conditions, which can be further exacerbated by limited water flow. Phytoplankton are key primary producers in estuaries. They move with the water bodies and can be flushed in and out with the tides . Their productivity is largely dependent upon the turbidity of

14848-648: The sub port of Los Angeles. After World War II, the United Nations was chartered in San Francisco, and in September 1951, the Treaty of San Francisco to re-establish peaceful relations between Japan and the Allied Powers was signed in San Francisco, entering into force a year later. In the years immediately following the war, the Bay Area saw a huge wave of immigration as populations increased across

14976-664: The time of colonization, the Ohlone peoples in the Bay Area primarily lived on the San Francisco Peninsula, in the South Bay and in the East Bay, and the Miwok primarily lived in the North Bay, northern East Bay, and Central Valley. Ohlone villages were spread across the Peninsula, East Bay, South Bay, as well as further south into the Monterey Bay area. There were eight major divisions of Ohlone people, four of which were based in

15104-537: The tip of the San Francisco Peninsula, the city of San Francisco is not considered part of the "Peninsula" subregion, but as a separate entity. The term "South Bay" has different meanings to different groups: Writing in 1959 for the Army Corps of Engineers , the United States Department of Commerce defined the South Bay as comprising five counties, corresponding to their two-way division of

15232-544: The titular city of San Francisco. Its eastern half, which runs alongside the Bay, is highly populated, while its less populated western coast traces the coastline of the Pacific Ocean and is known for its open space and hiking trails. Roughly coinciding with the borders of San Mateo County , it also includes the northwestern Santa Clara County cities of Palo Alto , Mountain View , and Los Altos . Although geographically located on

15360-456: The volume of freshwater, the tidal range, and the extent of evaporation of the water in the estuary. Drowned river valleys are also known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. Well-studied estuaries include

15488-453: The water and atmosphere, these organisms are also intaking all or nearly all of the available oxygen creating a hypoxic environment and unbalanced oxygen cycle . The excess carbon in the form of CO 2 can lead to low pH levels and ocean acidification , which is more harmful for vulnerable coastal regions like estuaries. Eutrophication has been seen to negatively impact many plant communities in estuarine ecosystems . Salt marshes are

15616-835: The water. The main phytoplankton present are diatoms and dinoflagellates which are abundant in the sediment. A primary source of food for many organisms on estuaries, including bacteria , is detritus from the settlement of the sedimentation. Of the thirty-two largest cities in the world in the early 1990s, twenty-two were located on estuaries. As ecosystems, estuaries are under threat from human activities such as pollution and overfishing . They are also threatened by sewage, coastal settlement, land clearance and much more. Estuaries are affected by events far upstream, and concentrate materials such as pollutants and sediments. Land run-off and industrial, agricultural, and domestic waste enter rivers and are discharged into estuaries. Contaminants can be introduced which do not disintegrate rapidly in

15744-535: The west coast of the Americas. Soromenho set sail on Manila Galleon San Agustin on July 5, 1595 and in early November they reached land between Point St. George and Trinidad Head , north of the Bay Area, in the Lost Coast . The expedition followed the coast southward and on November 7 the San Agustin anchored in Drakes Bay, and claimed the region as Puerto y Bahía de San Francisco . In late November,

15872-419: The western counties in the Bay Area, leaving only Alameda , Contra Costa , and Solano counties as remnants of a once large breeding range. Bald eagles were once common in the Bay Area, but habitat destruction and thinning of eggs from DDT poisoning reduced the California state population to 35 nesting pairs. Bald eagles disappeared from the Bay Area in 1915, and only began returning in recent years. In

16000-459: The winter season is cool and mild, the summer season is characterized by warm sunny days, while in San Francisco and areas closer to the Golden Gate strait, the summer season is periodically affected by fog. Due to the Bay Area's diverse topographic relief (itself the result of the clashing tectonic plates ), the region is home to numerous microclimates that lead to pronounced differences in climate and temperature over short distances. Within

16128-623: Was admitted as the 31st state in 1850. A major earthquake and fire leveled much of San Francisco in 1906. During World War II , the Bay Area played a major role in America's war effort in the Asiatic-Pacific Theater , with the San Francisco Port of Embarkation , of which Fort Mason was one of 14 installations and location of the headquarters, acting as a primary embarkation point for American forces. Since then,

16256-541: Was first reported in Redwood Creek at Muir Beach in 1996, has since been spotted in the North Bay's Corte Madera Creek , the South Bay's Coyote Creek , as well as in 2010 in San Francisco Bay itself at the Richmond Marina . Other mammals include the internationally famous sea lions who began inhabiting San Francisco's Pier 39 after the 1989 Loma Prieta earthquake and the locally famous Humphrey

16384-616: Was more than any other single factor, responsible for opening up the West and the San Francisco Bay Area, in particular, to world trade. By 1817 sea otter in the area were practically eliminated. Since then, the California golden beaver re-established a presence in Alhambra Creek , followed by the Napa River and Sonoma Creek in the north, and the Guadalupe River and Coyote Creek in the south. The North American river otter which

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