Belmont Slough is a

slough Slough () is a town and unparished area in the unitary authority of the same name in Berkshire, England, bordering west London. It lies in the Thames Valley, west of central London and north-east of Reading, at the intersection of the M4 ...

on the western shore of

San Francisco Bay San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water from a ...

separating

Redwood Shores Redwood Shores is a waterfront community in Redwood City, California, along the western shore of San Francisco Bay on the San Francisco Peninsula in San Mateo County, California, San Mateo County. Redwood Shores is the home of several major techn ...

and

Foster City Foster City is a city located in San Mateo County, California. The 2020 census put the population at 33,805, an increase of more than 10% over the 2010 census figure of 30,567. Foster City is sometimes considered to be part of Silicon Valley ...

. It provides

estuarine An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

and marine deepwater habitats in its subtidal waters, which are characterized as brackish and saltwater.

Course

The head of the slough is in

Belmont, California Belmont is a city in San Mateo County in the U.S. state of California. It is in the San Francisco Bay Area, on the San Francisco Peninsula about halfway between San Francisco and San Jose. Known for its wooded hills, views of the San Francisco ...

, just east of

U.S. Route 101 U.S. Route 101, or U.S. Highway 101 (US 101), is a north–south United States Numbered Highway that runs through the states of California, Oregon, and Washington, on the West Coast of the United States. It is also known as (The Royal Roa ...

, slightly north of the exit for Ralston Avenue / Marine Parkway. The slough takes a winding course generally northeast from there, passing to the north of the Redwood Shores

Oracle An oracle is a person or agency considered to provide wise and insightful counsel or prophetic predictions, most notably including precognition of the future, inspired by deities. As such, it is a form of divination. Description The word '' ...

campus (completed in 1989, formerly

Marine World/Africa USA Marine World/Africa USA was an animal theme park located in the Redwood Shores area of Redwood City, California. The park was named Marine World when it first opened in 1968 before merging with the failing land-animal park called Africa USA in 1 ...

) and south of Port Royal Park in Foster City. From there, the slough turns almost directly north, then east, then north again, and finally northeast as it enters the tidal exchange zone with the San Francisco Bay, an area characterized by shallow mudflats. Both the Foster City and Redwood Shores shorelines of Belmont Slough are protected by the

California Department of Fish and Wildlife The California Department of Fish and Wildlife (CDFW), formerly known as the California Department of Fish and Game (CDFG), is a state agency under the California Natural Resources Agency. The Department of Fish and Wildlife manages and protect ...

as the Redwood Shores Ecological Reserve, which is northwest of the adjacent

Don Edwards San Francisco Bay National Wildlife Refuge Don Edwards San Francisco Bay National Wildlife Refuge (DESFBNWR) is a United States National Wildlife Refuge located in the southern part of San Francisco Bay, California. The Refuge headquarters and visitor center is located in the Baylands dis ...

and Bair Island Ecological Reserve.

History

Redwood Shores Belmont Slough October 1970 R Forrester

In the early 1900s the slough was considered the best place to hunt ducks in

San Mateo County San Mateo County ( ), officially the County of San Mateo, is a county located in the U.S. state of California. As of the 2020 census, the population was 764,442. Redwood City is the county seat, and the third most populated city following Daly ...

, with the birds so plentiful, hunters could sneak up on them.

established the slough as a nature preserve in 1973. The main route of the

San Francisco Bay Trail The San Francisco Bay Trail is a bicycle and pedestrian trail that when finished will allow continuous travel around the shoreline of San Francisco Bay. As of 2020, of the trail have been completed. When finished, the trail will be over of p ...

runs along the perimeter of Foster City, including the western border along Belmont Slough. The city maintains several spur trails off the Bay Trail along the western shore of Belmont Slough, including trails that lead to a beach area and the Foster City sign, visible from aircraft landing at nearby

San Francisco International Airport San Francisco International Airport is an international airport in an unincorporated area of San Mateo County, south of Downtown San Francisco. It has flights to points throughout North America and is a major gateway to Europe, the Middle E ...

. The intake structure for the Foster City Lagoon, which provides flood control and recreational opportunities for the city, is at the western end of Angelo Slough; Angelo Slough is a stub waterway connected to Belmont Slough running east–west, just north of Bat Ray Island. The

California State Lands Commission The California State Lands Commission is a unit of state government that is responsible for management and protection of natural and cultural resources, as well as public access rights, on some of California's publicly owned lands. The members of ...

acquired the shoreline areas along Belmont Slough in an exchange with

Mobil Oil Corporation Mobil is a petroleum brand owned and operated by American oil and gas corporation ExxonMobil. The brand was formerly owned and operated by an oil and gas corporation of the same name, which itself merged with Exxon to form ExxonMobil in 1999. ...

in 1976.

Ecology

The salt marshes surrounding Belmont Slough contain stands of

cordgrass ''Spartina'' is a taxon of plants in the grass family, frequently found in coastal salt marshes. Its species are commonly known as cordgrass or cord-grass, and are native to the coasts of the Atlantic Ocean in western and southern Europe, north ...

and

pickleweed Pickleweed is a common name used for two unrelated genera of flowering plants: *'' Batis'', family Bataceae *''Salicornia ''Salicornia'' is a genus of succulent, halophytic (salt tolerant) flowering plants in the family Amaranthaceae that gro ...

and serve as feeding areas for rails, herons, and other shorebirds; the levees built to reclaim the land for Foster City and Redwood Shores host gum plant, which provides nesting grounds for the Bay salt marsh

song sparrow The song sparrow (''Melospiza melodia'') is a medium-sized New World sparrow. Among the native sparrows in North America, it is easily one of the most abundant, variable and adaptable species. Description Adult song sparrows have brown upperp ...

. Small rodents that live in the area are predated upon by the

white-tailed kite The white-tailed kite (''Elanus leucurus'') is a small raptor found in western North America and parts of South America. It replaces the related Old World black-winged kite in its native range. Taxonomy The white-tailed kite was described in 18 ...

short-eared owl The short-eared owl (''Asio flammeus'') is a widespread grassland species in the family Strigidae. Owls belonging to genus ''Asio'' are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or ...

, and

marsh harrier The marsh harriers are birds of prey of the harrier subfamily. They are medium-sized raptors and the largest and broadest-winged harriers. Most of them are associated with marshland and dense reedbeds. They are found almost worldwide, excluding o ...

. Other animals that may be found near Belmont Slough include the California black rail, California clapper rail, Western snowy plover, Alameda song sparrow, and pallid bat.

References

Bodies of water of San Mateo County, California San Francisco Bay {{SanMateoCountyCA-geo-stub