San Francisco Bay area is a major international shipping port, but it is only as deep as a swimming pool! Find out how that is possible
During the 1860’s and even into the early 20th century, vast quantities of mud and gravel from hydraulic mining operations were dumped into the upper Sacramento and San Joaquin Rivers.
The debris flowed down the rivers and eroded into a finer and finer sediment until it reached the bay system. It eventually filled in Suisun Bay, San Pablo Bay, and San Francisco Bay in varying degrees of severity.
The deep channels of San Francisco Bay are continually being dredged since the first decades of the 20th century to maintain a narrow deep channel through the much shallower bay. The average depth of San Francisco Bay is only as deep as a swimming pool at about 12 to 15 ft (3.7 to 4.6 m)!
Large ships travelling in the bay areas must therefore follow the deep underwater channels that are constantly being maintained by frequent dredging. The deepest part of the bay is under and out of the Golden Gate Bridge, at 372 ft (113 m).
Despite it being so shallow and thanks to continuous dredging, the Bay still serves as a major international shipping port, served by a large container facility operated by the Port of Oakland, and two smaller facilities in Richmond and San Francisco.