The Castro Rocks are several rocks in

Richmond, California Richmond is a city in western Contra Costa County, California, United States. The city was municipal corporation, incorporated on August 7, 1905, and has a Richmond, California City Council, city council.

, protruding from the waters in

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 ...

between

Castro Point Castro Point is a cape in western Richmond, California, United States. History Castro Point was once the east shore landing for the Richmond-San Rafael Car and Passenger Ferry that crossed the San Pablo Bay. It was also the western terminal for t ...

and

Red Rock Island Red Rock Island (variously known as ''Moleta'', Molate Rock, and Golden Rock ) is an uninhabited, island in the San Francisco Bay located just south of the Richmond–San Rafael Bridge. The property is the only privately owned island in San Fra ...

. The rocks lie almost directly under the Richmond-San Rafael Bridge ( I-580).Topographic map
TopoQuest, retrieved July 6, 2008

Name

The rocks are named after

Don Víctor Castro Don, don or DON and variants may refer to: Places *County Donegal, Ireland, Chapman code DON *Don (river), a river in European Russia *Don River (disambiguation), several other rivers with the name *Don, Benin, a town in Benin *Don, Dang, a vill ...

, a local rancho-era land owner. They are shown as "Castro Rocks" on an 1850 survey map of the

San Francisco Bay area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

made by Cadwalader Ringgold.

Harbor seals

Castro Rocks are the home of many

harbor seal The harbor (or harbour) seal (''Phoca vitulina''), also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere. The most widely distributed species of pinniped (walruses, eared sea ...

s,Tagging program
, SFSU, retrieved August 1, 2007 which lie on them to rest and sunbathe. The rocks are the largest harbor seal rookery in the northern San Francisco Bay and the second largest in the Bay Area itself.
, Castro Rocks page, retrieved August 1, 2007 There are also sometimes sea lions on the rocks.
, NOAA Press Release, February 12, 1999, retrieved August 4, 2007 The rock's Harbor Seals also frequent

Mowry Slough Mowry Slough is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed March 15, 2011 slough in Don Edwards San Francisco Bay National Wildlife Refuge and is the primary breeding ground for Sa ...

Brooks Island Brooks Island Regional Preserve includes both the of Brooks Island above the low-tide line and of the surrounding bay. The only public access to the island is via an East Bay Regional Park District naturalist tour. Brooks Island is a mostly fla ...

, Yerba Buena Island, and Mare Island.vhfmapweb.jpg
, Radio tagging map, San Francisco State University, February 2004, retrieved August 4, 2007 The seals at this location have high levels of toxic pollutants including the

DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...

, PCBs, PBDEs,

PFOS Perfluorooctanesulfonic acid (PFOS) (conjugate base perfluorooctanesulfonate) is a chemical compound having an eight-carbon fluorocarbon chain and a sulfonic acid functional group and thus a perfluorosulfonic acid. It is an anthropogenic (man ...

, PFOA, and

mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

.Harbor seals may help determine effect on humans of eating toxic fish
by Jane Kay, ''

San Francisco Chronicle The ''San Francisco Chronicle'' is a newspaper serving primarily the San Francisco Bay Area of Northern California. It was founded in 1865 as ''The Daily Dramatic Chronicle'' by teenage brothers Charles de Young and M. H. de Young, Michael H. de ...

'', 19-10-2009, access date 19-02-2009

References

External links

Castro Rocks page
- Photos {{San Francisco Bay watershed, state=autocollapse Geography of Richmond, California Islands of Contra Costa County, California Islands of San Francisco Bay Islands of Northern California Landforms of Contra Costa County, California Rock formations of California