Bolinas Lagoon Watershed
History and Habitat

Human Settlement

Beginning in the 19th century, dairy ranches were established in Rancho Las Baulines. Initially accessible only by boat or horseback, the watershed became more populated after the first road, built in 1870, connected the area to Sausalito.  

The community now known as Stinson Beach, located at the base of the western slope of Mt. Tamalpais, was originally populated by tent camps.  Later, a subdivision known as “Stinson Ranch” was developed and the first water system in the area was established to serve the subdivision.  Following the 1906 San Francisco earthquake, the area experienced an influx of residents and businesses.  Use of the area by tourists began in the early 20th century with day use at a County Park located on the beach.

Changes to Watershed Processes 

For over thirty years, local community groups and scientists have brought attention to the ecological value of the lagoon and the need to slow sediment deposition to preserve it.  The Bolinas Technical Advisory Committee was appointed by the County Board of Supervisors in 1974, and the Committee to Save Bolinas Lagoon was established in 1994 by the Bolinas Lagoon Foundation.  Working with local experts, the Committee to Save Bolinas Lagoon secured funds from Congress for initial studies for restoring the lagoon.  MCOSD developed a management plan to address the loss of tidal and subtidal habitat and sedimentation in Bolinas Lagoon in 1981, and revised the plan in 1996. 

In 2008, the Bolinas Lagoon Ecosystem Restoration Project: Recommendations for Restoration and Management was completed by a working group of community representatives and scientists, coordinated by the Gulf of the Farallones National Marine Sanctuary Advisory Council, with support from MOSD and USACE.  Restoration objectives and recommended actions include restoring natural sediment transport and ecological functions of the lagoon, identifying and managing non-native species, and protecting water quality.

Each of these restoration objectives are complemented by a set of management recommendations that include implementing best management practices throughout the watershed, removing fallen trees from the lagoon, establishing a public education program to reduce human disturbance of harbor seals, immediately removing introduced cordgrass found in the Lagoon, and developing emergency response plans to address the closure of the lagoon inlet or an oil spill. 

Historic land use activities that could and may still be contributing to the sedimentation problem in the lagoon are addressed in the Historical Perspective of Bolinas Lagoon Watershed (Van Kirk 2002 1).  The Bolinas Lagoon Watershed Study: Input Sediment Budget (Tetra Tech 2001 2) evaluates “the sources and magnitude of sediment delivered to the lagoon via erosional processes within the watershed.”  This study concluded that current erosion rates are near background (pre-1850) levels within the watershed. 

Easkoot Creek originates in the steep, west-facing slopes of Bolinas Ridge.  The three tributaries; Fitzhenry, Laurel, and Black Rock Creeks join to form Easkoot Creek just upstream of Shoreline Highway in Stinson Beach.  After exiting the uplands, the Creek turns northwest and flows behind the coastal dune until it enters the south arm of Bolinas Lagoon.  It has been debated whether or not the creek historically flowed to the Lagoon or went straight out to the ocean.  Recent research indicates that the current channel location very closely matches its historic location, and that only during high flow events would the creek change its course and flow directly to the ocean across the beach (Van Kirk 2002, Tetra Tech 2001).

Nearly 170 meters of Easkoot Creek through the town of Stinson Beach has riprap, SacCrete, gabions, or retaining walls stabilizing its banks (Fong 2002 3).  Over the years levees had been built up along lower Easkoot Creek, adjacent to Stinson Beach Park, with spoils from sediment dredging activities.  These artificial levees restricted hydrologic connectivity of the stream to its floodplains and adjacent wetlands.  This reach of creek also exhibited markedly low amounts of large wood and no viable pools (Fong 2002). 

The lower reach of Easkoot Creek flows through a tidal marsh located between Shoreline Hwy and Calle del Arroyo.  With the start of construction of the Seadrift lagoon and subdivision in 1960, and the presence of the delta at the mouth of Stinson Gulch, tidal circulation to the southeastern arm of Bolinas Lagoon was restricted.  Removal of the Stinson Gulch delta constriction and the restoration of a more natural tidal range allowed the marsh at the mouth of Easkoot Creek to nearly double in size between 1968 and 1998 (PWA 2006 4).

The steep slopes of the upper Easkoot watershed are prone to landslides.  Sediment derived from the hillslopes is transported to the low gradient and tidally influenced reaches where it is stored in the channel.  In order to maintain channel capacity, the National Park Service has had to remove sediment from the creek at Stinson Beach Park on a regular basis.

Habitat Types

Bolinas Lagoon represents a unique habitat within the watershed, consisting of mudflats, marshes, tidal channels, and a flood shoal island.  The primary vegetation communities within the watershed are coastal scrub, Douglas fir and redwood forest, and grasslands.  There are small patches of eucalyptus, oak and oak-bay woodlands, riparian scrub woodland, and pine cypress forest.

Easkoot Creek is located within one of the most biologically diverse and ecologically significant areas on the California coast.  The watershed supports a mix of upland and aquatic habitats.  It borders state and federal parks, private property, and local municipality lands.  Upland habitats are dominated by coast redwood and Douglas fir forest along the inner gorges, chaparral on the convex slopes, and grasslands with a strong native component (NPS 2003 5).  However, the riparian plant community along Easkoot Creek contains the largest number of non-native plants when compared with other east-side tributaries (Fong 2002).  Only isolated remnants of historic willow and alder forest remain.  The Easkoot Creek watershed is within the Pacific Flyway, “the major corridor for movement of migratory shorebirds, raptors, and other birds along the West Coast of North America” (NPS 2003). 

A complex of habitats supports a variety of species at the mouth of Easkoot Creek at Bolinas.  The finger of lagoon that extends to the mouth of Easkoot Creek, commonly referred to as south arm, supports saltmarsh habitat, frequently exposed mudflats, and subtidal channels, all bordered by development on the Stinson Beach Spit.  In recent years, saltmarsh habitat has been expanding in the south arm due to the restoration of a more natural tidal range following the removal of the constriction caused by the Stinson Gulch delta (PWA 2006).  This area serves as a nursery for fish, harbor seals haul out on the mudflats, rails are present, and an abundance of invertebrates provide a food source for shore and waterbirds (PWA 2006 6). 

Easkoot Creek drains into the east side of Bolinas Lagoon and is the second largest drainage in the watershed.  Several small tributaries (e.g., Fitzhenry, Laurel, and Black Rock Creeks) drain the upper watershed.  Much of the upper watershed is publicly owned and supports a mix of forested, chaparral, and grassland habitats.  The lower watershed is mostly privately owned and more heavily developed.  It is tidally influenced with saltmarsh forming the transition zone between mainstem Easkoot Creek and Bolinas Lagoon. 

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 and scrub along the Bolinas Lagoon Spit and in the vicinity of Stinson Beach. 

Noteworthy species in Bolinas Lagoon include clapper and black rails, salt marsh common yellowthroat, great egrets, and great blue herons occur around the lagoon, and California red-legged frog are known to occur adjacent to the lagoon in freshwater ponds.  The 1996 Bolinas Lagoon Management Plan Update identifies additional special-status species found in the Bolinas Lagoon watershed, including California brown pelican, American peregrine falcon, Point Reyes mountain beaver, and Point Reyes jumping mouse.

In Pine Gulch Creek, species include Coho salmon, steelhead trout, northern spotted owl, salt marsh common yellowthroat, black swift, California red-legged frog, and Marin manzanita are known to occur.  Since 1997, the National Park Service Coho Salmon and Steelhead Trout Restoration Program staff has been actively monitoring fish populations along 12 kilometers of mainstem Pine Gulch Creek.  Coho salmon were documented within the watershed in 1968, but monitoring by NPS staff failed to document a single Coho salmon from the fall of 1997 to the summer of 2000.  Since that time, Coho salmon have been documented annually by NPS staff in Pine Gulch Creek.  Since 2001, the highest number of adult spawners were observed during the 2004-2005 year class in which three adults and three redds were observed.  In 2007-2008, one Coho salmon and two redds were observed (NPS 2008 7). 

California red-legged frog and steelhead trout are known to occur in Wilkins Gulch. Steelhead trout are known to occur in Morse’s Gulch, McKinnon Gulch and Stinson Gulch. 

The Easkoot Creek subwatershed is known to support a remnant population of steelhead.  According to Fong (2002), the historic distribution of steelhead within the watershed is roughly similar to their distribution today.  However, the current population size does not reflect historic abundance.  The subwatershed may support California red-legged frog, federally listed as threatened and Species of Special Concern; however, there are no documented occurrences.  Red-legged frogs have been documented in a small brackish pond on the east side of Highway One in the north end of the lagoon. 

Human Habitation and Land Use

Much of the watershed is in public ownership. Private communities occur within the Pine Gulch Creek subwatershed, and some private parcels within Pine Gulch Creek are used for farming. Much of the Easkoot subwatershed is county, state, and federal parkland.  The Golden Gate National Recreation Area, formed in 1972, acquired most of the open land surrounding the community of Stinson Beach.  Other protected lands include Bolinas Lagoon and Mt. Tamalpais State Park. 

Organic farmers along Pine Gulch Creek are working to establish a cooperative agreement with local agencies to protect Coho salmon and steelhead trout habitat in the creek, while also maintaining local agriculture.  For more information, contact the Marin Resource Conservation District.

The watershed supports limited residential and commercial use.  Commercial uses are generally geared toward serving the large summer tourist population.  Stinson Beach residential use is at its peak in the summer, when single-family homes may be occupied by multiple families coming to the area for vacations.  While the community of Stinson Beach remains small (fewer than 1,000 residents) and seasonal occupancy remains a typical community feature, full-time residential use is increasing (Stetson 2006 8). 


1 Historical Perspective of Bolinas Bay (Lagoon) 

2 Bolinas Lagoon Watershed Study Input Sediment Budget

3 D. Fong. Fisheries Assessment For Bolinas Lagoon Tributaries within the Golden Gate National Recreation Area, 1995-2000

4 Phillip Williams and Associates. Projecting the Future Evolution of Bolinas Lagoon - Final Public Draft.

5 National Park Service. Environmental Assessment: Easkoot Creek Restoration at Stinson Beach

6 Phillip Williams and Associates. Projecting the Future Evolution of Bolinas Lagoon - Final Public Draft

7  http://science.nature.nps.gov/im/units/sfan/vital_signs/fish/docs/2007-08SpawnerSurveySummary.pdf

8 2005 Urban Water Management Plan