Gallinas Creek Watershed
History and Habitat

Human Settlement

Coast Miwok lived throughout the Santa Margarita valley.  The first rancho in the watershed was established in 1844 as a land grant to Timothy Murphy.  The grant included three ranchos, San Pedro, Santa Margarita and y Las Gallinas, with the Santa Margarita rancho roughly corresponding to the Gallinas Creek watershed.

With the establishment of the ranchos, grazing began in earnest.  Heavy grazing eventually led to loss of riparian vegetation and incising of the creeks.  In 1853, John Lucas inherited the 7,600-acre Santa Margarita Rancho, built a home, and continued grazing cattle.  He sold about 1,200 acres of the Rancho to Manuel Freitas in 1898, who continued to graze dairy cattle on the rich grasslands but also planted oat hay.  Dairy cattle grazing continued through most of the watershed into the 1900s.

In the early 1900s, the tidal marshes along the bayfront were diked and drained to create additional agricultural land.  In 1914, Mabry McMahan attempted to establish a Venetian-style city complete with gondolas in the area now known as Santa Venetia.  He got as far as building landfill, canals, and levees and establishing several structures, but wasn’t able to fulfill his vision; Santa Venetia and Santa Margarita Island Open Space Preserves retain part of that effort.  The first housing development in the watershed was established in the area and the Santa Venetia neighborhood remains an active inhabited area in the watershed.  

Further development in the valley areas west of Highway 101 began around 1950 and has continued as a mix of residential and commercial facilities.  By the mid-1960s most of the lower watershed was filled with urban development; by the mid-1970s the urban nature of the area was much like the present day.  The establishment of open space preserves along the ridge tops gave rise to a regrowth of riparian vegetation and many creeks in the upper watershed now have thick riparian growth.

aerial view of Gallinas

Aerial photo looking northeast towards the bay from above Hwy 101. January 16, 1973. DPW file photo.

Changes to Watershed Processes

Prior to urbanization and the tidal wetland reclamation practices of the early 1900s, Gallinas Creek was an extensive tidal slough system fed by intermittent streams originating above Santa Margarita Valley and the headlands surrounding South Gallinas slough.  By the 1940s the main tidal sloughs were leveed and the smaller channels and interior tidal marshes drained and filled for agricultural land (Kamman Hydrology and Engineering, Inc. 2004 ) creating the channel configuration present today. 

During the construction of the Terra Linda housing development in the 1950s Gallinas Creek and its tributaries in Santa Margarita Valley were channelized along Del Ganado Road and Freitas Parkway, following the historic creek alignment.  Tributaries to South Gallinas Slough were also channelized in the 1950s and 60s during the construction of Los Ranchitos and San Rafael Meadows.  From aerial photos it appears that channels in the upper watershed were incised and lacked riparian vegetation; characteristics of a heavily grazed watershed (Kamman Hydrology and Engineering, Inc. 2004).

Today the main Gallinas Creek channel in Santa Margarita Valley is a concrete-lined, trapezoidal flood control channel fed by storm drain outlets along its length.  Flow in the Gallinas Creek has become perennial due to residential irrigation runoff and the non-permeable concrete channel bed. 

Although the creeks that drain the southern portion of the Gallinas watershed have not been turned into trapezoidal concrete flood channels, they have been realigned and their banks heavily armored. 

Habitat Types

Historically, the Gallinas Creek watershed supported extensive native forests, healthy riparian systems, and expansive wetlands in the lower watershed. Currently, the watershed is highly urbanized and native communities have been fragmented and altered from their original condition.  The upper watershed is composed primarily of annual grasslands interspersed with mixed evergreen forest (including oak-bay woodland), coastal scrub, and small outcroppings of serpentine habitat.  The upper slopes are largely Marin County Open Space ridge lands.  In the upper watershed, where the channel is open and not restricted to underground culverts, the banks are typically dominated by non-native plants.

Along the southern watershed boundary, upslope of Santa Venetia, there is a large tract of oak-bay woodland which is continuous with China Camp State Park.  While not technically part of the Gallinas Creek watershed, China Camp State Park at the southeastern corner of the watershed supports a number of intact communities including extensive woodlands, grassy meadows, and pristine wetlands and special-status species, providing habitat connectivity between the two watersheds. 

Upstream of Highway 101 (upper watershed), the stream channel and tributaries are restricted to rectangular and trapezoidal channels and underground storm drains, respectively.  The upper slopes of the watershed are county-owned open space (Terra Linda – Sleepy Hollow Divide Open Space Preserve) and in these areas native uplands dominate.  Downstream of Highway 101 where the creek is tidally influenced, it is channelized.  Marshes adjacent to San Pablo Bay are leveed.  The lower creek-slough provides the most important biological resources within the watershed. The lower marsh habitats represent some of the largest remaining tidally influenced habitats in the bay region (Goals Project 1999 1). 

Fish and Wildlife

The lower watershed supports a number of special-status plants and animals.  Of particular interest are the occurrences of wetland-adapted species along the baylands.  Noteworthy species include San Pablo song sparrow, California black rail, salt marsh harvest mouse, and California clapper rail.  

Downstream of Highway 101, the creek is tidally influenced and forms a network of sloughs contained within man-made levees.  The north fork slough is adjacent to McInnis County Park.  The south fork slough originates downstream of the Marin County Civic Center, wraps around Santa Margarita Island Open Space Preserve, and then the community of Santa Venetia.  The two channels connect at Santa Venetia Open Space Preserve.  In this area, the tidal channels and adjacent salt water and brackish-water marshes support a number of animals.  Birdlife is abundant and waterfowl frequent the tidal sloughs. Rails and shorebirds are common along the edges in marsh habitat.  River otters are also known to frequent the area (Kamman Hydrology and Engineering, Inc. 2004 2).  The north mouth of Gallinas Creek, supports one of the largest populations of California clapper rail within San Pablo Bay (Herzog, et al., 2005 3).  Overall, the watershed is known to support 86 breeding bird species (Kamman Hydrology and Engineering, Inc. 2004).

Historically, the Gallinas Creek watershed may have supported steelhead and other fish.  Kamman Hydrology and Engineering, Inc. (2004) noted observations by Walter Freitas of steelhead swimming up main Gallinas Creek during the winter months.  Historical observations occurred at least as far as St. Isabella’s Church, upstream of Las Gallinas Avenue, at Trinity Avenue.  Currently, the upper Gallinas Creek watershed is not known to support fish due to a lack of habitat and perennial water.  The lower tidal sloughs likely support estuarine fish; however, there are no reports documenting their occurrence. 

There are no reported occurrences of federally-listed as threatened and California Species of Special Concern California red-legged frog within the watershed (CDFG 2008 4).  A U.S. Fish and Wildlife Service protocol site assessment for red-legged frogs was conducted at St. Vincent’s School in 2001 by LSA in adjacent Miller Creek (LSA 2001 5).  The assessment found only marginal habitat for this species and no historical or recent records of California red-legged frogs in this area. 

There are no reported occurrences of California Species of Special Concern northwestern pond turtle within the watershed (CDFG 2008).

Heron and egret nesting colonies have been monitored by Audubon Canyon Ranch since the early 1990s (Kelly, et al., 2006 6).  Up until recently, a colony of approximately 18 great blue herons nests occupied oak woodland habitat and a small redwood grove on private property off of North San Pedro Road.  The colony was abandoned after the 1996 breeding season.  A second colony on private property on North San Pedro Road has been monitored since 2002. It currently supports 1 to 3 great blue heron nests.  There is a single record of a great egret in 2002 at this location.  Mature eucalyptus trees are currently being utilized (Condenso, personal communication, May 15, 2008; Kelly, et al., 2006).

PRBO Conservation Science has been actively monitoring tidal marsh bird populations throughout the San Francisco Bay region since 1996.  The goal of the monitoring is to assess population status and trends of special-status birds and “model and predict the relative abundance and distribution of tidal marsh birds with respect to local habitat features, configuration, and surrounding landscapes patterns” (PRBO Conservation Science 2008 7).  Focal species include California clapper rail, California black rail, San Pablo song sparrow, salt marsh common yellowthroat, and marsh wren.  The study area for this work includes the tidal marshes of China Camp State Park (Liu, et al., 2007 8).

In 2005 and 2006, an estuary-wide study to determine temporal and spatial patterns in the California clapper rail population was conducted by PRBO Conservation Science and Avocet Research Associates (Herzog, et al., 2005).  This study was correlated with previous work completed in 1992 and 1993 within the San Pablo and Suisun Bays and population trends were evaluated.  Rails were monitored on north fork, south fork, and the mouth of Gallinas Creek.  Between initial observation in 1992 and the 2005 field season, clapper rail populations increased within the Gallinas Creek watershed 9.  

Human Habitation and Land Use

The Gallinas watershed is largely within the North San Rafael planning area.  The western ridge tops separating the watershed from the Miller Creek watershed to the north and San Rafael Creek watershed to the south are protected as County open space.  Moving downhill through the watershed, development becomes progressively denser, with the lowland areas east of Highway 101 supporting fully developed neighborhoods, shopping, schools, and hospital facilities.

Land protection and restoration efforts in the watershed include wetland restoration by the Marin Audubon Society and Marin Community Foundation, in partnership with other funders, that began in 1972 and were completed in 1977 restoring about three acres of filled land to tidal marsh.

The Friends of Gallinas Creek, San Pablo Watershed Restoration Program Partners, The Bay Institute and Marin County Stormwater Pollution Prevention Program (MCSTOPPP) are planning extensive restoration in the upper and lower watershed to improve riparian cover, provide habitat, reduce erosion, and restore wetlands.


1 Gallinas Creek Restoration Feasibilty Study and Conceptual Design Report Marin County, CA 

2 Baylands Ecosystem Habitat Goals: A Report of Habitat Recommendations

3 Gallinas Creek Restoration Feasibilty Study and Conceptual Design Report Marin County, CA

4 Temporal and Spatial Patterns in Population Trends in California Clapper Rail (Rallus longirostris obsoletus) 2005 Progress Report

5 California Department of Fish and Game (CDFG). 2008. California Natural Diversity Database. California Department of Fish and Game, Sacramento, CA. 

6 California Red-legged Frog Site Assessment: St. Vincents's School Property San Rafael, Marin County

7 Annotated Atlas and Implications for the Conservation of Heron and Egret Nesting Colonies in the San Francisco Bay Area

8 http://www.prbo.org/cms/135

9 2007 Annual Report: California Clapper Rail (Rallus longirostris obsoletus)