Richardson Bay Watershed
History and Habitat

Human settlement

The Richardson Bay watershed is located on the aboriginal lands of the Coast Miwok. The arrival of Europeans led to the Mexican government establishing a system of land ownership through which Miwok ancestral lands were divided into tracts of land known as ranchos. Much of the area was originally part of the lands of the Mission San Rafael Archangel, established in 1817. After the Mission was secularized in 1834, the land became the first Mexican land grant in the North Bay. The Rancho Corte Madera del Presidio (literally, “place where wood is cut for the Presidio”) included a sawmill for processing redwood trees, cattle and horse ranches, a brickyard, and a stone quarry.

The city of Mill Valley was incorporated in 1900; the largest single period of growth in the area came when San Franciscans relocated after the 1906 earthquake. Demand for forest resources increased throughout the 19th century; Mill Valley is named for the historic sawmill at Old Mill Park. As forest resources declined due to logging, the land was sub-divided and sold as building lots. In July 1929, a large wildfire burned for three days, consuming 100 homes before shifting winds spared downtown Mill Valley. Continuing demand for development in the area led to many wetlands along the Bay being filled to provide more acreage for construction of residential and commercial buildings, as well as the roads and bridges linking them.

The Sausalito area was explored by Europeans in 1775, when the Spanish ship San Carlos sailed into San Francisco Bay. These explorers named the area Saucelito (“little willows”) after the vegetation spotted from shipboard. Sausalito became an important ferry port, connecting Marin to San Francisco. The railroad brought supplies from the north to be shipped across San Francisco Bay. Marin City, at the north end of Sausalito, grew rapidly during World War II as it was developed for shipyard worker housing.

The Tiburon Peninsula was part of the original grant of Corte Madera del Presidio to John Thomas Reed. When California was admitted to the United States in 1850 after the Mexican war, Angel Island was retained by the government for military use. Military garrisons were established on the island in 1863, providing support to Angel Island and San Francisco military uses, including brickyards and powder companies. A military reservation was built on Peninsula Island (now Belvedere). This subwatershed was also used for ranching and fishing.

In 1852, Benjamin Buckelew laid out “California City” in the area now known as Paradise Cay. Oyster farming, started in Richardson Bay in 1866, lasted for 10 years and a codfish processing plant opened in 1877. A ferry ran from Tiburon to San Francisco and railroad lines connected the community to Sausalito and San Rafael. Shipbreaking and salvage became major industries in Tiburon during the 1880s.

Belvedere incorporated in 1893 and Tiburon in 1964. The entire Peninsula experienced an increase in residential growth after the 1906 earthquake and again when the Golden Gate Bridge opened in 1937. Angel Island went through many transformations, including use as an army hospital, recruit training area, staging area, discharge camp, quarantine station, and immigration station. After World War II, Angel Island was transferred to the Department of the Interior.

Watershed Today

Richardson Bay is considered one of the most “pristine estuaries on the Pacific Coast in spite of its urbanized periphery” (Richardson Bay Audubon 2008 1).  The Bay is recognized as an Important Bird Area (IBA) and is located on the Pacific Flyway, an important migratory bird corridor.  During the winter months, the Bay supports hundreds of thousands of waterbirds, including shorebirds and waterfowl.

Historically, the myriad of habitats in this watershed were connected to one another via the streams cascading down from Mt Tamalpais.  Creeks overflowed onto floodplain marshes and these wetlands transitioned into extensive native forests and grasslands.  Today, the upper slopes and ridges of the watershed remain largely protected from development, and redwood and Douglas fir forest, chaparral, and oak woodlands still dominate the hills.  These plant communities provide wildlife with natural movement corridors.  The diverse vegetation is a reflection of the soils, availability of water and micro-climates in the watershed.  The creeks and adjoining forest lands support steelhead trout and northern spotted owls.

The baylands and Richardson Bay still support a diverse array of native plants and animals.  Great blue heron and great egret nesting colonies are found along the Bay’s shoreline.  Bothin Marsh Open Space Preserve protects the largest salt marsh at the northern end of Richardson Bay.  Surrounded by cordgrass and pickleweed, the marsh supports many birds including the endangered California clapper rail, as well as the endangered salt marsh harvest mouse.

Fish and Wildlife

The watershed supports a number of special-status plants and animals.  Of particular interest are the occurrences of species found in coastal marsh in the lower watershed.  Noteworthy species include California black rail, San Pablo song sparrow, salt marsh harvest mouse, and Point Reyes bird’s-beak.  At higher elevations, northern spotted owl territories occur in wooded areas along several creeks.

There is a small population of California red-legged frog (CRLF), federally listed as threatened and a California Species of Special Concern, on the Tiburon Peninsula (CDFG 2008).  The population was discovered in 1997 at a small pond, formerly a lagoon, at Keil Cove.  A second sighting was made in 2000 in coast live oak woodland to the northwest of the Keil Cove sighting.  This is probably the last remaining population on the peninsula.

The Arroyo Corte Madera del Presidio subwatershed still supports a steelhead trout run. Old Mill and Cascade Creeks support the healthiest remaining fisheries habitat in the watershed.  Due to their ephemeral nature, the small creeks draining directly to Richardson Bay do not support sustainable fisheries.

The Arroyo Corte Madera del Presidio subwatershed is known to support nine fish species (seven native and two introduced).  Native species include California roach, Sacramento pikeminnow, Coho salmon, steelhead trout, threespine stickleback, and staghorn and prickly sculpins.  Introduced species include rainwater killifish and western mosquitofish (Leidy 2007 2).  Recorded observations of Coho date from the 1940s to 1960s; Coho were last seen in 1981 (Leidy, et al., 2005 3).  Steelhead, federally listed as a threatened species, continue to inhabit Arroyo Corte Madera del Presidio in reduced numbers.

Barriers to fish passage in our local creeks can consist of road crossings and undersized culverts when they block passage for fish at any life stage.  Fish passage considerations must be made for the young fish as well as adults.

Richardson Bay itself supports the second largest extant eelgrass bed in San Francisco Bay.  Eelgrass beds provide important shelter for fish and shellfish, and a food source for many water bird species.  Bay pipefish, bat ray, black surfperch, northern anchovy, Pacific herring, striped bass, and threespine stickleback are just a few of the many fish species found in the Bay.

In the winter, the Bay supports hundreds of thousands waterbirds including ducks, geese, grebes and shorebirds.  The Richardson Bay Audubon Center and Sanctuary manages a small upland parcel, supporting beach, bluffs, grasslands, oak woodland, coastal scrub, and riparian woodland, and 900 acres of submerged baylands.  The Center operates a Monitoring Avian Productivity and Survivorship (MAPS) bird-banding station during the breeding season.  Species captured and/or observed during the breeding season include Cooper’s hawk, Anna’s hummingbird, Pacific-slope flycatcher, black phoebe, western scrub-jay, chestnut-backed chickadee, bushtit, Bewick’s wren, Swainson’s thrush, northern mockingbird, Wilson’s warbler, spotted towhee, California towhee, dark-eyed junco, black-headed grosbeak, red-tailed hawk, mourning dove, American crow, common raven, barn swallow, cliff swallow, house finch.  In addition, the Center is working on eelgrass bed restoration, native oyster restoration, fish monitoring, water quality monitoring, and waterbird surveys.

Human habitation and land use 

Mill Valley land use is mostly medium to low density residential with clusters of commercial areas on the valley floors.  The upper slopes and ridges are largely owned by Marin County Open Space, Marin Municipal Water District, and state and federal park agencies; these lands provide habitat connectivity between adjoining watersheds.

The Coyote Creek area is bounded by Bothin Marsh and Richardson Bay to the east and the Arroyo Corte Madera del Presidio subwatershed to the north.  The ridges to the south and west are protected as part of the Golden Gate National Recreation Area.  The Coyote Creek subwatershed includes the unincorporated communities of Tamalpais Valley, Tamalpais Valley Junction (Tam Junction), Manzanita, and Almonte. 

Most of the development is single-family residential, with limited commercial development and services.  The upper watershed is mostly rural and semi-rural, while the lower watershed is developed with greater densities near Bothin Marsh.  Commercial development is largely concentrated in a small area at the junction of Highway 1 and Almonte Road.

Sausalito and Marin City both have a mix of residential and commercial areas.  The upper hillsides are almost entirely residential and there is a substantial houseboat residential area at along the bay front.  Marin City has less waterfront; commercial development is in the lower bayfront areas and the residential development is in the hills.

In addition to Tiburon and Belvedere, the Peninsula supports Bel Aire, Paradise Cay, and Strawberry Point.  Development is largely residential, with small commercial areas. The largest preserve in the watershed is Ring Mountain Preserve, located on Tiburon Ridge.  The Richardson Bay Audubon Center and Sanctuary manages an 11-acre upland parcel directly adjacent to Richardson Bay and 900 acres of submerged baylands.  This property supports beach, bluffs, grasslands, oak woodland, coastal scrub, and riparian woodland.


2 Ecology, Assemblage Structure, Distribution & Status of Fishes in Streams Tributary to the San Francisco Estuary

3 (Oncorhynchus mykiss) in Streams of the San Francisco Estuary, CA