Editing San Francisco Bay (section)

==Geography==
The bay covers somewhere between {{convert|400|and(-)|1600|sqmi|sigfig=1}}, depending on which sub-bays (such as San Pablo Bay), estuaries, [[wetland]]s, and so on are included in the measurement.<ref>{{cite web| url = http://www.sfmuseum.org/hist9/mcgloin.html| title = Symphonies in Steel: San Francisco – Oakland Bay Bridge and the Golden Gate<!-- Bot generated title -->| access-date = April 13, 2005| archive-date = May 4, 2015| archive-url = https://web.archive.org/web/20150504051900/http://www.sfmuseum.org/hist9/mcgloin.html| url-status = live}}</ref><ref>[http://response.restoration.noaa.gov/cpr/watershed/sanfrancisco/sfb_html/sfbenv.html San Francisco Bay Watershed Database and Mapping Project<!-- Bot generated title -->] {{webarchive |url=https://web.archive.org/web/20041030120227/http://response.restoration.noaa.gov/cpr/watershed/sanfrancisco/sfb_html/sfbenv.html |date=October 30, 2004 }}</ref><ref>{{Cite web|title=BCDC - The San Francisco Bay Estuary|url=https://bcdc.ca.gov/bay_estuary.html|access-date=February 14, 2022|website=bcdc.ca.gov|archive-date=February 17, 2022|archive-url=https://web.archive.org/web/20220217230941/https://www.bcdc.ca.gov/bay_estuary.html|url-status=live}}</ref> The main part of the bay measures {{convert|3|to(-)|12|mi|km|0|spell=in}} wide east-to-west and somewhere between {{convert|48|mi|km|0}}<sup>[[#References|1]]</sup> and {{convert|60|mi|km|0}}<sup>[[#References|2]]</sup> north-to-south.

San Francisco Bay is the second-largest estuary on the Pacific coast of the Americas, following the [[Salish Sea]] in Washington State and British Columbia, Canada.<ref>{{Cite web| last1 = Jeffrey Mount| last2 = Wim Kimmerer| title = The Largest Estuary on the West Coast of North America| work = California WaterBlog| access-date = 2024-08-17| date = 2022-12-18| url = https://californiawaterblog.com/2022/12/18/the-largest-estuary-on-the-west-coast-of-north-america/}}</ref>

The bay was navigable as far south as [[San Jose, California|San Jose]] until the 1850s, when [[hydraulic mining]] 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-19th century 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 [[harbor]], many thousands of acres of marshy wetlands at the edges of the bay were, for many years, considered wasted space. As a result, soil excavated for building projects or [[dredging|dredged]] from channels was often dumped onto the wetlands and other parts of the bay as landfill.{{citation needed|date=April 2024}}

From the mid-19th century through the late 20th century, more than a third of the original bay was filled and often built on. The deep, damp soil in these areas is subject to [[soil liquefaction]] during earthquakes, and most of the major damage close to the bay in the [[Loma Prieta earthquake]] of 1989 occurred to structures on these areas.{{citation needed|date=April 2024}}

The [[Marina District, San Francisco|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)|Panama-Pacific International Exposition]], although liquefaction did not occur on a large scale. In the 1990s, [[San Francisco International Airport]] proposed filling in hundreds more acres to extend its overcrowded international [[runway]]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|Bay fill and depth profile]]" section.'')

There are five large islands in San Francisco Bay. [[Alameda (island)|Alameda]], the largest island, was created when a shipping lane was cut to form the [[Port of Oakland]] in 1901. It is now a suburban community. [[Angel Island, California|Angel Island]] was known as "[[Ellis Island]] West" because it served as the entry point for immigrants from East Asia. It is now a state park accessible by ferry. Mountainous [[Yerba Buena Island]] is pierced by [[Yerba Buena Tunnel|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 Island, California|Treasure Island]], site of the 1939 [[Golden Gate International Exposition]]. From the Second World War until the 1990s, both islands served as military bases and are now being redeveloped. Isolated in the center of the bay is [[Alcatraz]], the site of the famous federal penitentiary. The federal prison on [[Alcatraz Island]] no longer functions, but the complex is a popular tourist site. Despite its name, [[Mare Island]] in the northern part of the bay is a peninsula rather than an island.

{{wide image|GGNRA-SF-panorama.jpg|1200px|Panorama of San Francisco Bay, and the city skyline seen from Marin County in the [[Golden Gate National Recreation Area]]}}