Gallinas Creek land use and habitat

North Fork

The North Fork is the larger of the two drainages. It flows from the western ridgeline through the Santa Margarita Valley and the community of Terra Linda to its confluence with South Gallinas Slough near McInnis Park.

South Gallinas Slough

South Gallinas Slough is fed by several small tributaries that originate in the San Rafael Hills and San Pedro Ridge and flow through the highly urbanized communities of San Rafael Meadows and Santa Venetia.

Historically, the Gallinas Creek watershed supported:

• Extensive native forests
• Healthy riparian systems
• Expansive wetlands in the lower watershed

Currently, the watershed is highly urbanized. Native plant communities have been fragmented and altered from their original condition.

Upper watershed

The upper watershed is composed primarily of:

• Annual nonnative grasslands interspersed with mixed evergreen forest and oak-bay woodland
• Coastal scrub
• Small outcroppings of serpentine habitat

The upper slopes of the watershed are largely within the County-owned Terra Linda – Sleepy Hollow Divide Open Space Preserve.

Upstream of Highway 101, the stream channel is restricted to rectangular and trapezoidal channels and tributaries are restricted to underground storm drains.

Downstream of Highway 101, the creek is channelized for a portion before regaining the natural channel. Some marshes adjacent to San Pablo Bay are leveed. The lower tidal marsh habitats represent some of the largest remaining tidally influenced habitats in the San Francisco Bay region and provides the most important biological resources within the watershed.

Along the southern watershed boundary, upslope of Santa Venetia, there is a large area of oak-bay woodland. This is continuous with China Camp State Park and provides important habitat for woodland species.

China Camp State Park

While not technically part of the Gallinas Creek watershed, China Camp State Park is located at the southeastern corner of the watershed and provides habitat connectivity between the two watersheds. It supports a number of intact natural communities including:

• Extensive woodlands
• Grassy meadows
• Pristine wetlands
• Special-status species

Special status species

The lower watershed marsh supports a number of special-status animals, including:

• San Pablo song sparrow
• Ridgway's rail (formerly called California clapper rail)
• California black rail
• Salt marsh harvest mouse

Mammals

Deer, coyotes, skunks, and raccoons are common mammals throughout the watershed. River otters are known to frequent the channels near the bay.

Birds

Birdlife is abundant and waterfowl frequent the tidal sloughs. Rails and shorebirds are common along the edges in marsh habitat. The mouth of Gallinas Creek supports one of the largest populations of Ridgway's rail within San Pablo Bay. Overall, the watershed is known to support 86 breeding bird species.

Herons and egrets are known to nest in the watershed.  Audubon Canyon Ranch has monitored heron and egret nesting colonies since the early 1990s.

Point Blue Conservation Science has been monitoring tidal marsh bird populations throughout the San Francisco Bay region since 1996, including the tidal marshes of Gallinas Creek watershed and China Camp State Park. The goal is to assess population status and trends of special-status birds and understand how  surrounding landscape patterns affect population success.

Tidal marsh species include:

• Ridgway's rail
• California black rail
• San Pablo song sparrow
• Salt marsh common yellowthroat
• Marsh wren

Point Blue Conservation Science and Avocet Research Associates conducted an estuary-wide study in 2005-06  to determine temporal and spatial population patterns of Ridgway's rail. The study was correlated with previous work completed in 1992 and 1993 within the San Pablo and Suisun Bays. Rails were monitored on north fork, south fork, and the mouth of Gallinas Creek. Overall, Ridgway's rail populations within the Gallinas Creek watershed increased between 1992 and 2006.

Fish

Historically, the Gallinas Creek watershed may have supported steelhead and other native fish species. 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.

Currently, the upper Gallinas Creek watershed is not known to support fish due to a lack of habitat. The lower tidal sloughs likely support estuarine fish. However, there are no reports documenting their occurrence.

Amphibians and reptiles

Western toads, Pacific tree frogs, gopher and garter snakes, and western fence lizards are common throughout the watershed.

There are no reported occurrences of California red-legged frog within the watershed. The red-legged frog is federally listed as threatened and a California Species of Special Concern.

A U.S. Fish and Wildlife Service protocol site assessment for red-legged frogs was conducted at St. Vincent’s School in 2001 in adjacent Miller Creek watershed. 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 northwestern pond turtle, a California Species of Special Concern, within the watershed.

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 Park. The south fork slough originates downstream of the Marin County Civic Center, and wraps around Santa Margarita Island Open Space Preserve and the community of Santa Venetia. The two channels connect at Santa Venetia Open Space Preserve near McInnis Park.

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. The flatter lower watershed is covered by suburban development. The lowland areas east of Highway 101 support fully developed neighborhoods, shopping, and schools.

Changes to the watershed

Environmental conditions and habitat in the Gallinas Creek watershed has changed significantly over the past 250 years.

Before 1900

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.  As European settlers began grazing cattle, the watershed lost riparian vegetation and creeks began to erode and incise.

1940s

By the 1940s, the main tidal sloughs had been leveed and the smaller channels and interior tidal marshes drained and filled for agricultural land creating the channel configuration present today.

1950s and 1960s

Residential development increased throughout the 1950s. During the construction of the Terra Linda neighborhood, Gallinas Creek and its tributaries were channelized along Del Ganado Road and Freitas Parkway. Tributaries to South Gallinas Slough were also channelized during the construction of the Los Ranchitos and San Rafael Meadows neighborhoods.

Present day

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 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 Creek watershed have not been turned into concrete flood channels, they have been realigned and their banks heavily armored.

Conservation and restoration

Several community groups and public agencies are working to improve watershed conditions.

The Marin Audubon Society and Marin Community Foundation, with other funders, restored three acres of filled land to tidal marsh in 1977.

Marin County Parks is currently planning a project at McInnis Park to reclaim historic tidelands and protect against sea level rise.

The Gallinas Watershed Council is working with Marin County Parks to install and monitor floating islands in the Civic Center Lagoon to improve water quality in the pond.