San Francisco Bay

The San Francisco Bay is a shallow, productive estuary in which water draining approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean. Technically, the Sacramento River flows into Suisun Bay, which flows through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay, which connects at its south end to San Francisco Bay, although the entire group of interconnected bays are often referred to as "the San Francisco Bay."

Size

The Bay covers somewhere between 400http://www.sfmuseum.org/hist9/mcgloin.html and 1600http://response.restoration.noaa.gov/cpr/watershed/sanfrancisco/sfb_html/sfbenv.html square miles (1040 to 4160 square kilometres), depending on which sub-bays (such as San Pablo Bay), estuaries, wetlands, 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 48 mi (77 km)1 and 60 mi (97 km)2 north-to-south. One difficulty in obtaining accurate measurements is that the wetlands and inlets of the bay have been gradually and deliberately filled in, changing the Bay's size since the mid-1800s by as much as one third or even more. Recently, large areas of wetlands have been restored, further confusing the issue of the Bay's size.

Related Topics:
Square kilometre - Estuaries - Wetland - 1 - 1800s

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Despite its value as a waterway and harbor, the many thousands of acres (several km²) 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 into 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 earthquakes, and most of the major damage close to the Bay in the Loma Prieta earthquake of 1989 occurred to structures on these areas. In the 1990s, the San Francisco International Airport proposed filling in hundreds more acres (km²) to extend its overcrowded international runways in exchange for purchasing other parts of the bay and converting them back to wetlands. The idea was, and remains, controversial.

Related Topics:
Harbor - Wetlands - 1800s - 1900s - Liquefaction - Earthquake - Loma Prieta earthquake - 1989 - 1990s - San Francisco International Airport - Runway

~ ~ ~ ~ ~ ~ ~ ~ ~ ~