San Rafael Creek is a watercourse in

Marin County, California Marin County is a County (United States), county located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 262,231. Its county seat and ...

, United States that discharges to

San Rafael Bay San Rafael Bay is an embayment of San Pablo Bay, located in Marin County and the northern San Francisco Bay Area, California.

, a small

embayment A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a narr ...

of the

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 ...

. The mouth of San Rafael Creek is a channelized

estuary 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 ...

through an industrial area. San Rafael Creek has a designation under Federal Law Section 303(d) as impaired by

diazinon Diazinon (IUPAC name: ''O'',''O''-Diethyl ''O''- -methyl-6-(propan-2-yl)pyrimidin-2-ylphosphorothioate, INN - Dimpylate), a colorless to dark brown liquid, is a thiophosphoric acid ester developed in 1952 by Ciba-Geigy, a Swiss chemical company ( ...

, the principal

pollutant A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...

causing impairment designations for streams discharging to

San Pablo Bay San Pablo Bay is a tidal estuary that forms the northern extension of San Francisco Bay in the East Bay and North Bay regions of the San Francisco Bay Area in northern California. Most of the Bay is shallow; however, there is a deep water ch ...

, which is the northern arm of

. In September 2007, the organization

Save The Bay Save The Bay is a nonprofit organization dedicated to preserving San Francisco Bay and its related estuarine habitat areas. Founded by Catherine Kerr, Sylvia McLaughlin, and Esther Gulick in 1961, the organization grew into a body that not onl ...

designated San Rafael Creek as one of the top ten "worst trash hot spot" waterways flowing into the San Francisco Bay. The channel portion of San Rafael Creek below the Grand Street Bridge is dredged on a regular maintenance schedule to keep the shallow draft channel navigable. Dredge spoils are disposed of at a site near

Alcatraz Island Alcatraz Island () is a small island in San Francisco Bay, offshore from San Francisco, California, United States. The island was developed in the mid-19th century with facilities for a lighthouse, a military fortification, and a military pris ...

Most of the soils in the lower watershed are

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

s and

bay mud Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacia ...

, resulting in a low transmissivity of

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

. Typical vertical soil profiles in the lower watershed are four to five feet of imported fill over 60 to 65 feet (18–20 meters) of bay mud set on a basement of

Franciscan The Franciscans are a group of related Mendicant orders, mendicant Christianity, Christian Catholic religious order, religious orders within the Catholic Church. Founded in 1209 by Italian Catholic friar Francis of Assisi, these orders include t ...

Sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

bedrock In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface mater ...

. At the mouth of San Rafael Creek, situated on the south bank, is Pickleweed Park, where shorebirds can be seen, particularly in the winter

migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...

season.Nature information on San Rafael Creek Watershed
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References

{{San Francisco Bay watershed Rivers of Marin County, California San Rafael, California Rivers of Northern California Tributaries of San Pablo Bay

See also

References